Sign In button greyed out after restarting during game

I am unable to log back in if I am in a game until the game ends. I get a message along the lines of "the client has been reverted to a previous version" even though it looks the same, and I'm unable to sign in after entering my password as the sign in button does not engage.

This is very annoying and disturbing issue because I googled it and found pages upon pages of people reporting this issue with NO RIOT response.

I am returning to the game after a long long hiatus to check out the current state of the game and I am NOT HAPPY. Won't be returning.