A
Welcome to Android Central! Which phone? Does this occur on both wi-fi and mobile data?
Go to Settings>Apps>All, select Google Play Store, and Clear Cache/Clear Data, then Force Stop. Do the same for Download Manager. Now try again.
If that does't help, go to Settings>Accounts, remove your Google account completely, then add it back again.
Despite clearing cache and data..force stopping google play,google play services and download manager and removing and adding account...problem remains...