Error: Suspicious namespace and prefix combination [NamespaceTypo]

[puretsang]

workspace/InstaMaterial/app/src/main/res/layout/activity_publish.xml:3: Error: Suspicious namespace and prefix combination [NamespaceTypo]
xmlns:app="http://schemas.android.com/tools"
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Explanation for issues of type "NamespaceTypo":
Accidental misspellings in namespace declarations can lead to some very
obscure error messages. This check looks for potential misspellings to help
track these down.

1 errors, 0 warnings
:app:lintVitalRelease FAILED

FAILURE: Build failed with an exception.

[Biplovkumar]

change the code xmlns:app="http://schemas.android.com/tools" with this:

xmlns:app="http://schemas.android.com/apk/res/android"

It may help u.