ERR_SPDY_PROTOCOL_ERROR’ is an error which appears in the Chrome browser. It leads the as This webpage is not available. Chrome users can’t access certain websites affected by this error. There are various reason for having this issue:-
1. An issue in Flush Sockets.
2. Use Chromes in Incognito Mode.
3. Use an old version of chrome browser.
4. VPN is on.
If this error appears in the chrome visit Fix Err Spdy Protocol Error Not Responding for the solution.