diff --git a/src/app/project/ontology/property-form/property-form.component.html b/src/app/project/ontology/property-form/property-form.component.html
index a587b8467d..8db346216a 100644
--- a/src/app/project/ontology/property-form/property-form.component.html
+++ b/src/app/project/ontology/property-form/property-form.component.html
@@ -72,34 +72,40 @@
 
         <!-- depending on type: display gui attribute -->
         <div *ngIf="showGuiAttr" [ngSwitch]="propertyInfo.propType.objectType">
-            <mat-form-field class="large-field property-type" *ngSwitchCase="dspConstants.ListValue">
-                <span matPrefix class="property-type-icon">
+            <mat-form-field class="large-field property-type ontology-form-field" *ngSwitchCase="dspConstants.ListValue">
+                <span matPrefix class="ontology-prefix-icon">
                     <mat-icon>{{guiAttrIcon}}</mat-icon>&nbsp;
                 </span>
-                <mat-label>Select list</mat-label>
+                <mat-label>Select list *</mat-label>
                 <mat-select formControlName="guiAttr">
                     <mat-option *ngFor="let item of lists" [value]="item.id">
                         {{item.labels[0].value}}
                     </mat-option>
                 </mat-select>
+                <mat-hint *ngIf="formErrors.guiAttr">
+                    {{formErrors.guiAttr}}
+                </mat-hint>
             </mat-form-field>
 
-            <mat-form-field class="large-field property-type" *ngSwitchCase="dspConstants.LinkValue">
-                <span matPrefix class="property-type-icon">
+            <mat-form-field class="large-field property-type ontology-form-field" *ngSwitchCase="dspConstants.LinkValue">
+                <span matPrefix class="ontology-prefix-icon">
                     <mat-icon>{{guiAttrIcon}}</mat-icon>&nbsp;
                 </span>
-                <mat-label>Select resource class</mat-label>
+                <mat-label>Select resource class *</mat-label>
                 <mat-select formControlName="guiAttr">
                     <mat-option *ngFor="let item of resourceClasses" [value]="item.id">
                         {{item.label}}
                     </mat-option>
                 </mat-select>
+                <mat-hint *ngIf="formErrors.guiAttr">
+                    {{formErrors.guiAttr}}
+                </mat-hint>
             </mat-form-field>
 
             <!-- the gui-attribute for integer and decimal are not yet supported in the app -->
-            <mat-form-field class="large-field property-type"
+            <mat-form-field class="large-field property-type ontology-form-field"
                 *ngSwitchCase="propertyInfo.propType.objectType === dspConstants.IntValue || propertyInfo.propType.objectType === dspConstants.DecimalValue">
-                <span matPrefix class="property-type-icon">
+                <span matPrefix class="ontology-prefix-icon">
                     <mat-icon>{{guiAttrIcon}}</mat-icon>&nbsp;
                 </span>
                 <mat-label>Define range</mat-label>
diff --git a/src/app/project/ontology/property-form/property-form.component.ts b/src/app/project/ontology/property-form/property-form.component.ts
index 162f7b0c79..5a454336f5 100644
--- a/src/app/project/ontology/property-form/property-form.component.ts
+++ b/src/app/project/ontology/property-form/property-form.component.ts
@@ -8,6 +8,7 @@ import {
     IHasProperty,
     KnoraApiConnection,
     ListNodeInfo,
+    PropertyDefinition,
     ReadOntology,
     ResourceClassDefinitionWithAllLanguages,
     ResourcePropertyDefinitionWithAllLanguages,
@@ -141,23 +142,32 @@ export class PropertyFormComponent implements OnInit {
                 // a) in case of link value:
                 // set list of resource classes from response; needed for linkValue
                 this.resourceClasses = response.getAllClassDefinitions();
+                const resourceProperties = response.getAllPropertyDefinitions();
+
+                // set list of all existing resource property names to avoid same name twice
+                resourceProperties.forEach((resProp: PropertyDefinition) => {
+                    const name = this._os.getNameFromIri(resProp.id);
+                    this.existingNames.push(
+                        new RegExp('(?:^|W)' + name.toLowerCase() + '(?:$|W)')
+                    );
+                });
+
+                // add all resource classes to the same list
+                this.resourceClasses.forEach((resClass: ClassDefinition) => {
+                    const name = this._os.getNameFromIri(resClass.id);
+                    this.existingNames.push(
+                        new RegExp('(?:^|W)' + name.toLowerCase() + '(?:$|W)')
+                    );
+                });
 
-                // set list of all existing property names to avoid same name twice
-                Object.entries(this.ontology.properties).forEach(
-                    ([key]) => {
-                        const name = this._os.getNameFromIri(key);
-                        this.existingNames.push(
-                            new RegExp('(?:^|W)' + name.toLowerCase() + '(?:$|W)')
-                        );
-                    }
-                );
             },
             (error: ApiResponseError) => {
                 this._errorHandler.showMessage(error);
             }
         );
 
-        // b) in case of list value:
+        // b) in case of list value:s
+
         // set list of lists; needed for listValue
         this._cache.get('currentOntologyLists').subscribe(
             (response: ListNodeInfo[]) => {
diff --git a/src/app/project/ontology/resource-class-form/resource-class-form.component.ts b/src/app/project/ontology/resource-class-form/resource-class-form.component.ts
index 37a813948b..34bb34518a 100644
--- a/src/app/project/ontology/resource-class-form/resource-class-form.component.ts
+++ b/src/app/project/ontology/resource-class-form/resource-class-form.component.ts
@@ -2,8 +2,10 @@ import { AfterViewChecked, ChangeDetectorRef, Component, EventEmitter, Inject, I
 import { FormBuilder, FormControl, FormGroup, Validators } from '@angular/forms';
 import {
     ApiResponseError,
+    ClassDefinition,
     CreateResourceClass,
     KnoraApiConnection,
+    PropertyDefinition,
     ReadOntology,
     ResourceClassDefinitionWithAllLanguages,
     StringLiteral,
@@ -146,17 +148,25 @@ export class ResourceClassFormComponent implements OnInit, AfterViewChecked {
 
                 this.lastModificationDate = this.ontology.lastModificationDate;
 
-                // get all ontology resource classes:
-                // can be used to select resource class as gui attribute in link property,
-                // but also to avoid same name which should be unique
-                Object.entries(this.ontology.classes).forEach(
-                    ([key]) => {
-                        const name = this._os.getNameFromIri(key);
-                        this.existingNames.push(
-                            new RegExp('(?:^|W)' + name.toLowerCase() + '(?:$|W)')
-                        );
-                    }
-                );
+                const resourceClasses = response.getAllClassDefinitions();
+                const resourceProperties = response.getAllPropertyDefinitions();
+
+                // set list of all existing resource class names to avoid same name twice
+                resourceClasses.forEach((resClass: ClassDefinition) => {
+                    const name = this._os.getNameFromIri(resClass.id);
+                    this.existingNames.push(
+                        new RegExp('(?:^|W)' + name.toLowerCase() + '(?:$|W)')
+                    );
+                });
+
+                // add all resource properties to the same list
+                resourceProperties.forEach((resProp: PropertyDefinition) => {
+                    const name = this._os.getNameFromIri(resProp.id);
+                    this.existingNames.push(
+                        new RegExp('(?:^|W)' + name.toLowerCase() + '(?:$|W)')
+                    );
+                });
+
             },
             (error: ApiResponseError) => {
                 this._errorHandler.showMessage(error);