Google Play Store Error Code 504 & how to fix them

Google Play Store Error Code 504

First solution

The usual, please: go to Settings > Apps > All > Google Play Store and Clear cache and Clear data. Also Clear cache and Clear data for Google Services Framework.

Second solution

Try removing your Gmail account

Google Play Store Error Code 505

Solution

You need to find that whatapps has that some permission and trying to install & uninstall problems app.you find apk file for the trying to install and restore app and using a backup.

Google Play Store Error Code 491

Solution

Remove your Google account by going to the Settings for your device, then Accounts and Google. Hit Remove account. Reboot your Android and add the account once again. Next, in the Settings, go to Apps and swipe to All. Scroll down to Google Services, then click Clear data and finally Force stop.