Android Motionlayout: Android resource linking failed

If even upgrading ConstraintLayout doesn't help, try to add format attribute to your attr declaration in your attrs.xml file.

<resources>
    <attr name="yourAttrName" format="string" />
</resources>

Choose proper format for your attribute.

This problem is related to Android Studio 3.6 and ConstraintLayout versions earlier than 2.0.0-beta3 - I've reported the issue here. This is fixed in ConstraintLayout 2.0.0-beta3.

Android Studio 3.5 doesn't produce this error.

To make it work in AS 3.6 beta, upgrade to ConstraintLayout 2.0.0-beta3 or later.