File storage permission is enabled by default on the app setting, I even checked this before I posted this topic. Only permission to camera is not enabled, but camera has nothing to do with storage. Although, I enabled the camera's permission also and still the same error. All permissions enabled and yet the same error.
Open the files and make sure that you can access this folder.
/data/data/org.electrum.electrum/files/data/wallets
If you can't then you probably deleted it by mistakeز
if you can access your 12 words, save them, delete your wallet and reinstall it.