Google Play store error 921

"Error 921" happen wheen you're downloading,or update app from Google play.

this error is similar with error 498,but error 921 is concerned with your google mail account.

How to fix error 921?

• Clear cache memory out from your android devices :

(Go to Settings > Apps > All > Google Play Store > Clear Cache & Clear Data)

• Remove your google account from android devices :

(Go to Settings > Accounts & Sync >your google account > click menu  > Remove Google Account)

• Re-add your google account again, after this step  you can download any apps you want again from GOOGLE PLAY