diff --git a/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.html b/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.html
index 5e811ca5e..2511ef23c 100644
--- a/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.html
+++ b/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.html
@@ -16,7 +16,7 @@
         <mat-error *ngIf="valueFormControl.hasError('valueNotChanged')">
                  <span class="custom-error-message">New value must be different than the current value.</span>
             </mat-error>
-        <mat-error *ngIf="valueFormControl.hasError('invalidType')">
+        <mat-error *ngIf="valueRequiredValidator && valueFormControl.hasError('invalidType')">
                  <span class="custom-error-message">New value must be a valid resource type.</span>
         </mat-error>
         <mat-error *ngIf="valueFormControl.hasError('duplicateValue')">
diff --git a/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.spec.ts b/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.spec.ts
index 6800c940c..d518ee46f 100644
--- a/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.spec.ts
+++ b/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.spec.ts
@@ -22,564 +22,622 @@ import { LinkValueComponent } from './link-value.component';
  * Test host component to simulate parent component.
  */
 @Component({
-  template: `
+    template: `
     <dsp-link-value #inputVal [displayValue]="displayInputVal" [mode]="mode" [parentResource]="parentResource"
                     [propIri]="propIri" (referredResourceClicked)="refResClicked($event)" (referredResourceHovered)="refResHovered($event)"></dsp-link-value>`
 })
 class TestHostDisplayValueComponent implements OnInit {
 
-  @ViewChild('inputVal') inputValueComponent: LinkValueComponent;
+    @ViewChild('inputVal') inputValueComponent: LinkValueComponent;
 
-  displayInputVal: ReadLinkValue;
-  parentResource: ReadResource;
-  propIri: string;
-  mode: 'read' | 'update' | 'create' | 'search';
-  linkValueClicked: ReadLinkValue;
-  linkValueHovered: ReadLinkValue;
+    displayInputVal: ReadLinkValue;
+    parentResource: ReadResource;
+    propIri: string;
+    mode: 'read' | 'update' | 'create' | 'search';
+    linkValueClicked: ReadLinkValue;
+    linkValueHovered: ReadLinkValue;
 
-  ngOnInit() {
+    ngOnInit() {
 
-    MockResource.getTestThing().subscribe(res => {
-      const inputVal: ReadLinkValue =
-        res.getValuesAs('http://0.0.0.0:3333/ontology/0001/anything/v2#hasOtherThingValue', ReadLinkValue)[0];
+        MockResource.getTestThing().subscribe(res => {
+            const inputVal: ReadLinkValue =
+                res.getValuesAs('http://0.0.0.0:3333/ontology/0001/anything/v2#hasOtherThingValue', ReadLinkValue)[0];
 
-      this.displayInputVal = inputVal;
-      this.propIri = this.displayInputVal.property;
-      this.parentResource = res;
-      this.mode = 'read';
-    });
+            this.displayInputVal = inputVal;
+            this.propIri = this.displayInputVal.property;
+            this.parentResource = res;
+            this.mode = 'read';
+        });
 
-  }
+    }
 
-  refResClicked(readLinkValue: ReadLinkValue) {
-    this.linkValueClicked = readLinkValue;
-  }
+    refResClicked(readLinkValue: ReadLinkValue) {
+        this.linkValueClicked = readLinkValue;
+    }
 
-  refResHovered(readLinkValue: ReadLinkValue) {
-    this.linkValueHovered = readLinkValue;
-  }
+    refResHovered(readLinkValue: ReadLinkValue) {
+        this.linkValueHovered = readLinkValue;
+    }
 }
 
 /**
  * Test host component to simulate parent component.
  */
 @Component({
-  template: `
+    template: `
     <dsp-link-value #inputVal [mode]="mode" [parentResource]="parentResource" [propIri]="propIri"></dsp-link-value>`
 })
 class TestHostCreateValueComponent implements OnInit {
 
-  @ViewChild('inputVal') inputValueComponent: LinkValueComponent;
-  parentResource: ReadResource;
-  propIri: string;
-  mode: 'read' | 'update' | 'create' | 'search';
+    @ViewChild('inputVal') inputValueComponent: LinkValueComponent;
+    parentResource: ReadResource;
+    propIri: string;
+    mode: 'read' | 'update' | 'create' | 'search';
 
-  ngOnInit() {
+    ngOnInit() {
 
-    MockResource.getTestThing().subscribe(res => {
-      this.propIri = 'http://0.0.0.0:3333/ontology/0001/anything/v2#hasOtherThingValue';
-      this.parentResource = res;
-      this.mode = 'create';
-    });
-  }
+        MockResource.getTestThing().subscribe(res => {
+            this.propIri = 'http://0.0.0.0:3333/ontology/0001/anything/v2#hasOtherThingValue';
+            this.parentResource = res;
+            this.mode = 'create';
+        });
+    }
+}
+
+/**
+ * Test host component to simulate parent component.
+ */
+@Component({
+    template: `
+    <dsp-link-value #inputVal [mode]="mode" [parentResource]="parentResource" [propIri]="propIri" [valueRequiredValidator]="false"></dsp-link-value>`
+})
+class TestHostCreateValueNoValueRequiredComponent implements OnInit {
+
+    @ViewChild('inputVal') inputValueComponent: LinkValueComponent;
+    parentResource: ReadResource;
+    propIri: string;
+    mode: 'read' | 'update' | 'create' | 'search';
+
+    ngOnInit() {
+        MockResource.getTestThing().subscribe(res => {
+            this.propIri = 'http://0.0.0.0:3333/ontology/0001/anything/v2#hasOtherThingValue';
+            this.parentResource = res;
+            this.mode = 'create';
+        });
+    }
 }
 
 describe('LinkValueComponent', () => {
 
-  beforeEach(async(() => {
-    const valuesSpyObj = {
-      v2: {
-        search: jasmine.createSpyObj('search', ['doSearchByLabel']),
-      }
-    };
-    TestBed.configureTestingModule({
-      declarations: [
-        LinkValueComponent,
-        TestHostDisplayValueComponent,
-        TestHostCreateValueComponent
-      ],
-      imports: [
-        ReactiveFormsModule,
-        MatInputModule,
-        MatAutocompleteModule,
-        BrowserAnimationsModule
-      ],
-      providers: [
-        {
-          provide: DspApiConnectionToken,
-          useValue: valuesSpyObj
-        }
-      ]
-    })
-      .compileComponents();
-  }));
-
-  describe('display and edit a link value', () => {
-    let testHostComponent: TestHostDisplayValueComponent;
-    let testHostFixture: ComponentFixture<TestHostDisplayValueComponent>;
-    let valueComponentDe: DebugElement;
-    let valueInputDebugElement: DebugElement;
-    let valueInputNativeElement;
-    let valueReadModeDebugElement: DebugElement;
-    let valueReadModeNativeElement;
-    let commentInputDebugElement: DebugElement;
-    let commentInputNativeElement;
-
-    beforeEach(() => {
-      testHostFixture = TestBed.createComponent(TestHostDisplayValueComponent);
-      testHostComponent = testHostFixture.componentInstance;
-      testHostFixture.detectChanges();
-
-      expect(testHostComponent).toBeTruthy();
-      expect(testHostComponent.inputValueComponent).toBeTruthy();
-
-      const hostCompDe = testHostFixture.debugElement;
-
-      valueComponentDe = hostCompDe.query(By.directive(LinkValueComponent));
-      valueReadModeDebugElement = valueComponentDe.query(By.css('.rm-value'));
-      valueReadModeNativeElement = valueReadModeDebugElement.nativeElement;
+    beforeEach(async(() => {
+        const valuesSpyObj = {
+            v2: {
+                search: jasmine.createSpyObj('search', ['doSearchByLabel']),
+            }
+        };
+        TestBed.configureTestingModule({
+            declarations: [
+                LinkValueComponent,
+                TestHostDisplayValueComponent,
+                TestHostCreateValueComponent,
+                TestHostCreateValueNoValueRequiredComponent
+            ],
+            imports: [
+                ReactiveFormsModule,
+                MatInputModule,
+                MatAutocompleteModule,
+                BrowserAnimationsModule
+            ],
+            providers: [
+                {
+                    provide: DspApiConnectionToken,
+                    useValue: valuesSpyObj
+                }
+            ]
+        })
+            .compileComponents();
+    }));
 
-    });
+    describe('display and edit a link value', () => {
+        let testHostComponent: TestHostDisplayValueComponent;
+        let testHostFixture: ComponentFixture<TestHostDisplayValueComponent>;
+        let valueComponentDe: DebugElement;
+        let valueInputDebugElement: DebugElement;
+        let valueInputNativeElement;
+        let valueReadModeDebugElement: DebugElement;
+        let valueReadModeNativeElement;
+        let commentInputDebugElement: DebugElement;
+        let commentInputNativeElement;
 
-    it('should display an existing value', fakeAsync(() => {
+        beforeEach(() => {
+            testHostFixture = TestBed.createComponent(TestHostDisplayValueComponent);
+            testHostComponent = testHostFixture.componentInstance;
+            testHostFixture.detectChanges();
 
-      expect(testHostComponent.inputValueComponent.displayValue.linkedResourceIri).toEqual('http://rdfh.ch/0001/0C-0L1kORryKzJAJxxRyRQ');
-      expect(testHostComponent.inputValueComponent.displayValue.linkedResource.label).toEqual('Sierra');
+            expect(testHostComponent).toBeTruthy();
+            expect(testHostComponent.inputValueComponent).toBeTruthy();
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+            const hostCompDe = testHostFixture.debugElement;
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('read');
+            valueComponentDe = hostCompDe.query(By.directive(LinkValueComponent));
+            valueReadModeDebugElement = valueComponentDe.query(By.css('.rm-value'));
+            valueReadModeNativeElement = valueReadModeDebugElement.nativeElement;
 
-      expect(testHostComponent.inputValueComponent.valueFormControl.value instanceof ReadResource).toBe(true);
-      expect(testHostComponent.inputValueComponent.valueFormControl.value.label).toEqual('Sierra');
+        });
 
-      // setValue has to be called, otherwise the native input field does not get the label via the displayWith function
-      const res = testHostComponent.inputValueComponent.valueFormControl.value;
-      testHostComponent.inputValueComponent.valueFormControl.setValue(res);
+        it('should display an existing value', fakeAsync(() => {
 
-      // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+            expect(testHostComponent.inputValueComponent.displayValue.linkedResourceIri).toEqual('http://rdfh.ch/0001/0C-0L1kORryKzJAJxxRyRQ');
+            expect(testHostComponent.inputValueComponent.displayValue.linkedResource.label).toEqual('Sierra');
 
-      expect(valueReadModeNativeElement.innerText).toEqual('Sierra');
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
 
-      const anchorDebugElement = valueReadModeDebugElement.query(By.css('a'));
-      expect(anchorDebugElement.nativeElement).toBeDefined();
+            expect(testHostComponent.inputValueComponent.mode).toEqual('read');
 
-    }));
+            expect(testHostComponent.inputValueComponent.valueFormControl.value instanceof ReadResource).toBe(true);
+            expect(testHostComponent.inputValueComponent.valueFormControl.value.label).toEqual('Sierra');
 
-    it('should make a link value editable', fakeAsync(() => {
+            // setValue has to be called, otherwise the native input field does not get the label via the displayWith function
+            const res = testHostComponent.inputValueComponent.valueFormControl.value;
+            testHostComponent.inputValueComponent.valueFormControl.setValue(res);
 
-      testHostComponent.mode = 'update';
-      testHostFixture.detectChanges();
-      valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
-      valueInputNativeElement = valueInputDebugElement.nativeElement;
+            // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('update');
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            expect(valueReadModeNativeElement.innerText).toEqual('Sierra');
 
-      const update = new ReadResource();
-      update.id = 'newId';
-      update.label = 'new target';
+            const anchorDebugElement = valueReadModeDebugElement.query(By.css('a'));
+            expect(anchorDebugElement.nativeElement).toBeDefined();
 
-      testHostComponent.inputValueComponent.valueFormControl.setValue(update);
+        }));
 
-      // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+        it('should make a link value editable', fakeAsync(() => {
 
-      expect(valueInputNativeElement.value).toEqual('new target');
+            testHostComponent.mode = 'update';
+            testHostFixture.detectChanges();
+            valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
+            valueInputNativeElement = valueInputDebugElement.nativeElement;
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+            expect(testHostComponent.inputValueComponent.mode).toEqual('update');
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
+            const update = new ReadResource();
+            update.id = 'newId';
+            update.label = 'new target';
 
-      expect(updatedValue instanceof UpdateLinkValue).toBeTruthy();
+            testHostComponent.inputValueComponent.valueFormControl.setValue(update);
 
-      expect((updatedValue as UpdateLinkValue).linkedResourceIri).toEqual('newId');
+            // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-    }));
+            expect(valueInputNativeElement.value).toEqual('new target');
 
-    it('should compare the existing version of a link to the user input', () => {
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
 
-      // Sierra, http://rdfh.ch/0001/0C-0L1kORryKzJAJxxRyRQ
-      const initValue: ReadResource = testHostComponent.inputValueComponent.getInitValue();
+            const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
 
-      const readRes1 = new ReadResource();
-      readRes1.id = 'http://rdfh.ch/0001/0C-0L1kORryKzJAJxxRyRQ';
-      readRes1.label = 'Sierra';
+            expect(updatedValue instanceof UpdateLinkValue).toBeTruthy();
 
-      expect(
-          testHostComponent.inputValueComponent.standardValueComparisonFunc(
-              initValue, readRes1
-          )
-      ).toBeTruthy();
+            expect((updatedValue as UpdateLinkValue).linkedResourceIri).toEqual('newId');
 
-      const readRes2 = new ReadResource();
-      readRes2.id = 'newId';
-      readRes2.label = 'new target';
+        }));
 
-      expect(
-        testHostComponent.inputValueComponent.standardValueComparisonFunc(
-            initValue, readRes2
-        )
-      ).toBeFalsy();
+        it('should compare the existing version of a link to the user input', () => {
 
-      expect(
-          testHostComponent.inputValueComponent.standardValueComparisonFunc(
-              initValue, null
-          )
-      ).toBeFalsy();
+            // Sierra, http://rdfh.ch/0001/0C-0L1kORryKzJAJxxRyRQ
+            const initValue: ReadResource = testHostComponent.inputValueComponent.getInitValue();
 
-      expect(
-          testHostComponent.inputValueComponent.standardValueComparisonFunc(
-              initValue, 'searchlabel'
-          )
-      ).toBeFalsy();
+            const readRes1 = new ReadResource();
+            readRes1.id = 'http://rdfh.ch/0001/0C-0L1kORryKzJAJxxRyRQ';
+            readRes1.label = 'Sierra';
 
-    });
+            expect(
+                testHostComponent.inputValueComponent.standardValueComparisonFunc(
+                    initValue, readRes1
+                )
+            ).toBeTruthy();
 
-    it('should search for resources by their label', () => {
+            const readRes2 = new ReadResource();
+            readRes2.id = 'newId';
+            readRes2.label = 'new target';
 
-      const valuesSpy = TestBed.inject(DspApiConnectionToken);
-      (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
-        () => {
-          const res = new ReadResource();
-          res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
-          res.label = 'hidden thing';
-          return of(new ReadResourceSequence([res]));
-        }
-      );
+            expect(
+                testHostComponent.inputValueComponent.standardValueComparisonFunc(
+                    initValue, readRes2
+                )
+            ).toBeFalsy();
 
-      // simulate user searching for label 'thing'
-      testHostComponent.inputValueComponent.valueFormControl.setValue('thing');
+            expect(
+                testHostComponent.inputValueComponent.standardValueComparisonFunc(
+                    initValue, null
+                )
+            ).toBeFalsy();
 
-      expect(valuesSpy.v2.search.doSearchByLabel).toHaveBeenCalledWith('thing', 0, { limitToResourceClass: 'http://0.0.0.0:3333/ontology/0001/anything/v2#Thing' });
-      expect(testHostComponent.inputValueComponent.resources.length).toEqual(1);
-      expect(testHostComponent.inputValueComponent.resources[0].id).toEqual('http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ');
-    });
+            expect(
+                testHostComponent.inputValueComponent.standardValueComparisonFunc(
+                    initValue, 'searchlabel'
+                )
+            ).toBeFalsy();
 
-    it('should not return an invalid update value (string)', () => {
+        });
 
-      const valuesSpy = TestBed.inject(DspApiConnectionToken);
+        it('should search for resources by their label', () => {
 
-      (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
-        () => {
-          const res = new ReadResource();
-          res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
-          res.label = 'hidden thing';
-          return of(new ReadResourceSequence([res]));
-        }
-      );
+            const valuesSpy = TestBed.inject(DspApiConnectionToken);
+            (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
+                () => {
+                    const res = new ReadResource();
+                    res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+                    res.label = 'hidden thing';
+                    return of(new ReadResourceSequence([res]));
+                }
+            );
 
-      testHostComponent.mode = 'update';
-      testHostFixture.detectChanges();
-      valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
-      valueInputNativeElement = valueInputDebugElement.nativeElement;
+            // simulate user searching for label 'thing'
+            testHostComponent.inputValueComponent.valueFormControl.setValue('thing');
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('update');
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            expect(valuesSpy.v2.search.doSearchByLabel).toHaveBeenCalledWith('thing', 0, { limitToResourceClass: 'http://0.0.0.0:3333/ontology/0001/anything/v2#Thing' });
+            expect(testHostComponent.inputValueComponent.resources.length).toEqual(1);
+            expect(testHostComponent.inputValueComponent.resources[0].id).toEqual('http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ');
+        });
 
-      testHostComponent.inputValueComponent.valueFormControl.setValue('my string');
+        it('should not return an invalid update value (string)', () => {
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            const valuesSpy = TestBed.inject(DspApiConnectionToken);
 
-      const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
+            (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
+                () => {
+                    const res = new ReadResource();
+                    res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+                    res.label = 'hidden thing';
+                    return of(new ReadResourceSequence([res]));
+                }
+            );
 
-      expect(updatedValue).toBeFalsy();
+            testHostComponent.mode = 'update';
+            testHostFixture.detectChanges();
+            valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
+            valueInputNativeElement = valueInputDebugElement.nativeElement;
 
-    });
+            expect(testHostComponent.inputValueComponent.mode).toEqual('update');
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-    it('should not return an invalid update value (no value)', () => {
+            testHostComponent.inputValueComponent.valueFormControl.setValue('my string');
 
-      const valuesSpy = TestBed.inject(DspApiConnectionToken);
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
-        () => {
-          const res = new ReadResource();
-          res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
-          res.label = 'hidden thing';
-          return of(new ReadResourceSequence([res]));
-        }
-      );
+            const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
 
-      testHostComponent.mode = 'update';
-      testHostFixture.detectChanges();
-      valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
-      valueInputNativeElement = valueInputDebugElement.nativeElement;
+            expect(updatedValue).toBeFalsy();
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('update');
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+        });
 
-      testHostComponent.inputValueComponent.valueFormControl.setValue(null);
+        it('should not return an invalid update value (no value)', () => {
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            const valuesSpy = TestBed.inject(DspApiConnectionToken);
 
-      const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
+            (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
+                () => {
+                    const res = new ReadResource();
+                    res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+                    res.label = 'hidden thing';
+                    return of(new ReadResourceSequence([res]));
+                }
+            );
 
-      expect(updatedValue).toBeFalsy();
+            testHostComponent.mode = 'update';
+            testHostFixture.detectChanges();
+            valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
+            valueInputNativeElement = valueInputDebugElement.nativeElement;
 
-    });
+            expect(testHostComponent.inputValueComponent.mode).toEqual('update');
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-    it('should validate an existing value with an added comment', () => {
+            testHostComponent.inputValueComponent.valueFormControl.setValue(null);
 
-      testHostComponent.mode = 'update';
-      testHostFixture.detectChanges();
-      valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
-      valueInputNativeElement = valueInputDebugElement.nativeElement;
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      commentInputDebugElement = valueComponentDe.query(By.css('textarea.comment'));
-      commentInputNativeElement = commentInputDebugElement.nativeElement;
+            const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('update');
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            expect(updatedValue).toBeFalsy();
 
-      commentInputNativeElement.value = 'this is a comment';
-      commentInputNativeElement.dispatchEvent(new Event('input'));
-      testHostFixture.detectChanges();
+        });
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
-      const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
-      expect(updatedValue instanceof UpdateLinkValue).toBeTruthy();
-      expect((updatedValue as UpdateLinkValue).valueHasComment).toEqual('this is a comment');
+        it('should validate an existing value with an added comment', () => {
 
-    });
+            testHostComponent.mode = 'update';
+            testHostFixture.detectChanges();
+            valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
+            valueInputNativeElement = valueInputDebugElement.nativeElement;
 
-    it('should restore the initially displayed value', fakeAsync(() => {
+            commentInputDebugElement = valueComponentDe.query(By.css('textarea.comment'));
+            commentInputNativeElement = commentInputDebugElement.nativeElement;
 
-      testHostComponent.mode = 'update';
+            expect(testHostComponent.inputValueComponent.mode).toEqual('update');
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      testHostFixture.detectChanges();
+            commentInputNativeElement.value = 'this is a comment';
+            commentInputNativeElement.dispatchEvent(new Event('input'));
+            testHostFixture.detectChanges();
 
-      valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
-      valueInputNativeElement = valueInputDebugElement.nativeElement;
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+            const updatedValue = testHostComponent.inputValueComponent.getUpdatedValue();
+            expect(updatedValue instanceof UpdateLinkValue).toBeTruthy();
+            expect((updatedValue as UpdateLinkValue).valueHasComment).toEqual('this is a comment');
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('update');
+        });
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+        it('should restore the initially displayed value', fakeAsync(() => {
 
-      // simulate user input
-      const update = new ReadResource();
-      update.id = 'newId';
-      update.label = 'new target';
+            testHostComponent.mode = 'update';
 
-      testHostComponent.inputValueComponent.valueFormControl.setValue(update);
+            testHostFixture.detectChanges();
 
-      // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+            valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
+            valueInputNativeElement = valueInputDebugElement.nativeElement;
 
-      expect(valueInputNativeElement.value).toEqual('new target');
+            expect(testHostComponent.inputValueComponent.mode).toEqual('update');
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      testHostComponent.inputValueComponent.resetFormControl();
+            // simulate user input
+            const update = new ReadResource();
+            update.id = 'newId';
+            update.label = 'new target';
 
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+            testHostComponent.inputValueComponent.valueFormControl.setValue(update);
 
-      expect(valueInputNativeElement.value).toEqual('Sierra');
+            // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            expect(valueInputNativeElement.value).toEqual('new target');
 
-    }));
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
 
-    it('should set a new display value', fakeAsync(() => {
+            testHostComponent.inputValueComponent.resetFormControl();
 
-      // setValue has to be called, otherwise the native input field does not get the label via the displayWith function
-      const res = testHostComponent.inputValueComponent.valueFormControl.value;
-      testHostComponent.inputValueComponent.valueFormControl.setValue(res);
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-      // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+            expect(valueInputNativeElement.value).toEqual('Sierra');
 
-      expect(testHostComponent.inputValueComponent.valueFormControl.value.label).toEqual('Sierra');
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      const linkedRes = new ReadResource();
-      linkedRes.id = 'newId';
-      linkedRes.label = 'new target';
+        }));
 
-      const newLink = new ReadLinkValue();
-      newLink.id = 'updatedId';
-      newLink.linkedResourceIri = 'newId';
-      newLink.linkedResource = linkedRes;
+        it('should set a new display value', fakeAsync(() => {
 
-      testHostComponent.displayInputVal = newLink;
+            // setValue has to be called, otherwise the native input field does not get the label via the displayWith function
+            const res = testHostComponent.inputValueComponent.valueFormControl.value;
+            testHostComponent.inputValueComponent.valueFormControl.setValue(res);
 
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+            // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-      expect(valueReadModeNativeElement.innerText).toEqual('new target');
+            expect(testHostComponent.inputValueComponent.valueFormControl.value.label).toEqual('Sierra');
 
-    }));
+            const linkedRes = new ReadResource();
+            linkedRes.id = 'newId';
+            linkedRes.label = 'new target';
 
-    it('should emit the displayValue when the value is clicked on', () => {
+            const newLink = new ReadLinkValue();
+            newLink.id = 'updatedId';
+            newLink.linkedResourceIri = 'newId';
+            newLink.linkedResource = linkedRes;
 
-        expect(testHostComponent.linkValueClicked).toBeUndefined();
+            testHostComponent.displayInputVal = newLink;
 
-        valueReadModeNativeElement.click();
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-        expect(testHostComponent.linkValueClicked).toEqual(testHostComponent.displayInputVal);
-    });
+            expect(valueReadModeNativeElement.innerText).toEqual('new target');
+
+        }));
 
-    it('should emit the displayValue when the value is hovered', () => {
+        it('should emit the displayValue when the value is clicked on', () => {
 
-        expect(testHostComponent.linkValueHovered).toBeUndefined();
+            expect(testHostComponent.linkValueClicked).toBeUndefined();
 
-        valueReadModeNativeElement.dispatchEvent(
-            new MouseEvent('mouseover', {
-                view: window,
-                bubbles: true,
-                cancelable: true
-            })
-        );
+            valueReadModeNativeElement.click();
+
+            expect(testHostComponent.linkValueClicked).toEqual(testHostComponent.displayInputVal);
+        });
+
+        it('should emit the displayValue when the value is hovered', () => {
+
+            expect(testHostComponent.linkValueHovered).toBeUndefined();
+
+            valueReadModeNativeElement.dispatchEvent(
+                new MouseEvent('mouseover', {
+                    view: window,
+                    bubbles: true,
+                    cancelable: true
+                })
+            );
+
+            expect(testHostComponent.linkValueHovered).toEqual(testHostComponent.displayInputVal);
+        });
 
-        expect(testHostComponent.linkValueHovered).toEqual(testHostComponent.displayInputVal);
     });
 
-  });
+    describe('create a new link value', () => {
+        let testHostComponent: TestHostCreateValueComponent;
+        let testHostFixture: ComponentFixture<TestHostCreateValueComponent>;
 
-  describe('create a new link value', () => {
-    let testHostComponent: TestHostCreateValueComponent;
-    let testHostFixture: ComponentFixture<TestHostCreateValueComponent>;
+        let valueComponentDe: DebugElement;
 
-    let valueComponentDe: DebugElement;
+        let valueInputDebugElement: DebugElement;
+        let valueInputNativeElement;
+        let commentInputDebugElement: DebugElement;
+        let commentInputNativeElement;
 
-    let valueInputDebugElement: DebugElement;
-    let valueInputNativeElement;
-    let commentInputDebugElement: DebugElement;
-    let commentInputNativeElement;
+        beforeEach(() => {
 
-    beforeEach(() => {
+            testHostFixture = TestBed.createComponent(TestHostCreateValueComponent);
+            testHostComponent = testHostFixture.componentInstance;
+            testHostFixture.detectChanges();
 
-      testHostFixture = TestBed.createComponent(TestHostCreateValueComponent);
-      testHostComponent = testHostFixture.componentInstance;
-      testHostFixture.detectChanges();
+            expect(testHostComponent).toBeTruthy();
+            expect(testHostComponent.inputValueComponent).toBeTruthy();
 
-      expect(testHostComponent).toBeTruthy();
-      expect(testHostComponent.inputValueComponent).toBeTruthy();
+            const hostCompDe = testHostFixture.debugElement;
 
-      const hostCompDe = testHostFixture.debugElement;
+            valueComponentDe = hostCompDe.query(By.directive(LinkValueComponent));
 
-      valueComponentDe = hostCompDe.query(By.directive(LinkValueComponent));
+            valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
+            valueInputNativeElement = valueInputDebugElement.nativeElement;
 
-      valueInputDebugElement = valueComponentDe.query(By.css('input.value'));
-      valueInputNativeElement = valueInputDebugElement.nativeElement;
+            commentInputDebugElement = valueComponentDe.query(By.css('textarea.comment'));
+            commentInputNativeElement = commentInputDebugElement.nativeElement;
+        });
 
-      commentInputDebugElement = valueComponentDe.query(By.css('textarea.comment'));
-      commentInputNativeElement = commentInputDebugElement.nativeElement;
-    });
+        it('should search a new value', () => {
+            const valuesSpy = TestBed.inject(DspApiConnectionToken);
 
-    it('should search a new value', () => {
-      const valuesSpy = TestBed.inject(DspApiConnectionToken);
+            (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
+                () => {
+                    const res = new ReadResource();
+                    res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+                    res.label = 'hidden thing';
+                    return of(new ReadResourceSequence([res]));
+                }
+            );
 
-      (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
-        () => {
-          const res = new ReadResource();
-          res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
-          res.label = 'hidden thing';
-          return of(new ReadResourceSequence([res]));
-        }
-      );
+            testHostComponent.inputValueComponent.searchByLabel('thing');
+            testHostFixture.detectChanges();
 
-      testHostComponent.inputValueComponent.searchByLabel('thing');
-      testHostFixture.detectChanges();
+            expect(testHostComponent.inputValueComponent.mode).toEqual('create');
+            expect(valuesSpy.v2.search.doSearchByLabel).toHaveBeenCalledWith('thing', 0, { limitToResourceClass: 'http://0.0.0.0:3333/ontology/0001/anything/v2#Thing' });
+            expect(testHostComponent.inputValueComponent.resources.length).toEqual(1);
+        });
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('create');
-      expect(valuesSpy.v2.search.doSearchByLabel).toHaveBeenCalledWith('thing', 0, { limitToResourceClass: 'http://0.0.0.0:3333/ontology/0001/anything/v2#Thing' });
-      expect(testHostComponent.inputValueComponent.resources.length).toEqual(1);
-    });
+        it('should create a value', () => {
 
-    it('should create a value', () => {
+            // simulate user input
+            const res = new ReadResource();
+            res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+            res.label = 'hidden thing';
 
-      // simulate user input
-      const res = new ReadResource();
-      res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
-      res.label = 'hidden thing';
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            testHostComponent.inputValueComponent.valueFormControl.setValue(res);
 
-      testHostComponent.inputValueComponent.valueFormControl.setValue(res);
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+            expect(testHostComponent.inputValueComponent.valueFormControl.value instanceof ReadResource).toBeTruthy();
 
-      expect(testHostComponent.inputValueComponent.valueFormControl.value instanceof ReadResource).toBeTruthy();
+            const newValue = testHostComponent.inputValueComponent.getNewValue();
+            expect(newValue instanceof CreateLinkValue).toBeTruthy();
+            expect((newValue as CreateLinkValue).linkedResourceIri).toEqual('http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ');
+        });
 
-      const newValue = testHostComponent.inputValueComponent.getNewValue();
-      expect(newValue instanceof CreateLinkValue).toBeTruthy();
-      expect((newValue as CreateLinkValue).linkedResourceIri).toEqual('http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ');
-    });
+        it('should only create a new value if input is a resource', () => {
+            // simulate user input
+            const valuesSpy = TestBed.inject(DspApiConnectionToken);
 
-    it('should only create a new value if input is a resource', () => {
-      // simulate user input
-      const valuesSpy = TestBed.inject(DspApiConnectionToken);
+            (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
+                () => {
+                    const res = new ReadResource();
+                    res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+                    res.label = 'hidden thing';
+                    return of(new ReadResourceSequence([res]));
+                }
+            );
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      (valuesSpy.v2.search as jasmine.SpyObj<SearchEndpointV2>).doSearchByLabel.and.callFake(
-        () => {
-          const res = new ReadResource();
-          res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
-          res.label = 'hidden thing';
-          return of(new ReadResourceSequence([res]));
-        }
-      );
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            const label = 'thing';
+            testHostComponent.inputValueComponent.valueFormControl.setValue(label);
 
-      const label = 'thing';
-      testHostComponent.inputValueComponent.valueFormControl.setValue(label);
+            expect(testHostComponent.inputValueComponent.valueFormControl.value instanceof ReadResource).toBeFalsy();
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      expect(testHostComponent.inputValueComponent.valueFormControl.value instanceof ReadResource).toBeFalsy();
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            const newValue = testHostComponent.inputValueComponent.getNewValue();
 
-      const newValue = testHostComponent.inputValueComponent.getNewValue();
+            expect(newValue instanceof CreateLinkValue).toBeFalsy();
+        });
 
-      expect(newValue instanceof CreateLinkValue).toBeFalsy();
-    });
+        it('should reset form after cancellation', fakeAsync(() => {
 
-    it('should reset form after cancellation', fakeAsync(() => {
+            // simulate user input
+            const res = new ReadResource();
+            res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+            res.label = 'hidden thing';
+            testHostComponent.inputValueComponent.valueFormControl.setValue(res);
 
-      // simulate user input
-      const res = new ReadResource();
-      res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
-      res.label = 'hidden thing';
-      testHostComponent.inputValueComponent.valueFormControl.setValue(res);
+            // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-      // https://github.com/angular/components/blob/29e74eb9431ba01d951ee33df554f465609b59fa/src/material/autocomplete/autocomplete.spec.ts#L2577-L2580
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+            expect(valueInputNativeElement.value).toEqual('hidden thing');
 
-      expect(valueInputNativeElement.value).toEqual('hidden thing');
+            commentInputNativeElement.value = 'created comment';
 
-      commentInputNativeElement.value = 'created comment';
+            commentInputNativeElement.dispatchEvent(new Event('input'));
 
-      commentInputNativeElement.dispatchEvent(new Event('input'));
+            testHostFixture.detectChanges();
 
-      testHostFixture.detectChanges();
+            expect(testHostComponent.inputValueComponent.mode).toEqual('create');
 
-      expect(testHostComponent.inputValueComponent.mode).toEqual('create');
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+            testHostComponent.inputValueComponent.resetFormControl();
 
-      testHostComponent.inputValueComponent.resetFormControl();
+            testHostFixture.detectChanges();
+            tick();
+            testHostFixture.detectChanges();
 
-      testHostFixture.detectChanges();
-      tick();
-      testHostFixture.detectChanges();
+            expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
 
-      expect(testHostComponent.inputValueComponent.form.valid).toBeFalsy();
+            expect(testHostComponent.inputValueComponent.valueFormControl.value).toEqual(null);
 
-      expect(testHostComponent.inputValueComponent.valueFormControl.value).toEqual(null);
+            expect(valueInputNativeElement.value).toEqual('');
+            expect(commentInputNativeElement.value).toEqual('');
 
-      expect(valueInputNativeElement.value).toEqual('');
-      expect(commentInputNativeElement.value).toEqual('');
+        }));
+    });
 
-    }));
-  });
+    describe('create a new link value no value required', () => {
+        let testHostComponent: TestHostCreateValueNoValueRequiredComponent;
+        let testHostFixture: ComponentFixture<TestHostCreateValueNoValueRequiredComponent>;
+
+        beforeEach(() => {
+
+            testHostFixture = TestBed.createComponent(TestHostCreateValueNoValueRequiredComponent);
+            testHostComponent = testHostFixture.componentInstance;
+            testHostFixture.detectChanges();
+
+            expect(testHostComponent).toBeTruthy();
+        });
+
+        it('should create a value', () => {
+
+            // simulate user input
+            const res = new ReadResource();
+            res.id = 'http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ';
+            res.label = 'hidden thing';
+
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+
+            testHostComponent.inputValueComponent.valueFormControl.setValue(res);
+
+            expect(testHostComponent.inputValueComponent.form.valid).toBeTruthy();
+
+            expect(testHostComponent.inputValueComponent.valueFormControl.value instanceof ReadResource).toBeTruthy();
+
+            const newValue = testHostComponent.inputValueComponent.getNewValue();
+            expect(newValue instanceof CreateLinkValue).toBeTruthy();
+            expect((newValue as CreateLinkValue).linkedResourceIri).toEqual('http://rdfh.ch/0001/IwMDbs0KQsaxSRUTl2cAIQ');
+        });
+    });
 });
diff --git a/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.ts b/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.ts
index c68cf1f55..c722f72f7 100644
--- a/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.ts
+++ b/projects/dsp-ui/src/lib/viewer/values/link-value/link-value.component.ts
@@ -23,7 +23,7 @@ import { DspApiConnectionToken } from '../../../core/core.module';
 import { BaseValueComponent } from '../base-value.component';
 
 export function resourceValidator(control: AbstractControl) {
-    const invalid = !(control.value instanceof ReadResource);
+    const invalid = !(control.value === null || control.value === '' || control.value instanceof ReadResource);
     return invalid ? { invalidType: { value: control.value } } : null;
 }