Android APK crashes on launch with 'Illegal class access' error

Update:

@headsvk answer is now correct. Android studio didn't automatically prompted me to update the gradle so I had to do it manually. You have to use gradle 6.5.1 (change this in gradle-wrapper.properties file) and then change the com.android.tools.build:gradle version to 4.1.1 (in build.gradle file in project root). Clean and rebuild the project and it should be fixed.

Old answer:

I found a temporary way to fix this issue for myself. I realized that disabling proguard fixes the problem. So I just added a rule to tell proguard to keep androidx.appcompat class.

To do so, just add this line of code to proguard-rules.pro file:

-keep class androidx.appcompat.** { *; }

I got the same error, simply updating to the latest Androidx libraries solved the issue.