Android Studio unresolved reference. Project compiles

Question

After upgrading Android Studio, a project with no issues started showing issues in the editor. I have lots of Unresolved Reference errors. Anything under the su

Answer 1

I had the same problem. It is related with new AndroidX libraries and migration on it.

Try File -> Open -> and click build.gradle to reopen project.

Answer 2

Please Delete the .idea and .gradle project from the app directory and Invalidate and Cache Restart the Android Studio. This will resolve this issue.

Answer 3

Simple Solution Is That:

1: GoTo File And Close The Project.

2: Then GoTo File And Click On "Open Recent" And Open Your Project.

That Trick Works For Me.

Answer 4

I agree with Stanislav Mukhametshin that may be it is related with new AndroidX libraries and migration on it. I had cleaned and rebuilt project but that didn't work. So, I tried this way and error goes away.

1) Go to File and close project.

2) Reopen the same project.