This guide will let you know how to fix the Google Play Store Error Code -20. If you get the error code -21 on the Google play store, the first tip is to delete the unnecessary apps or cache files.
Go to the application manager and clear apps data.
The second tip is to restart your mobile phone.
You have to go to your application manager, click on the Google play store, “clear data,” and uninstall the updates. Now it is expected that your problem is fixed.
If not, you can remove all your google accounts and re-login!
After that, start the Google play store again to log in, and hopefully, you can download all applications now!