If you just downloaded an APK from web and in the installing process or when you were trying to run the installed APK and got an error “xAPK file validation error”, then you are in the right place.
To fix xAPK file validation error follow bellow steps:
Step 1: Uninstall the application
Step 2: Delete data files of this app from android/obb and android/data folders
Step 3: Copy and Install again the app, don’t run it.
Step 4: Through “My Files” on your phone or through a “File Explorer” app, navigate to Obb folder and copy the data of your installed app to external “sdcard/android/obb/*
Step 5: Run the game!