Warm Up Mode Error: 33906

If you try to join the Warm Up Mode, sometimes it gives out the error described as "33906" which can be closed with the "Ok" button on the screen of this error.

Unfortunately I was unable to screenshot the window per "print" button.

After that error , you are unable to join any room , respectively the game gets stucked when the window saying "Connecting to room ... Please wait !" occurs. Thus I have to restart the game.

The error (33906) occurs more than usually expected, but I might think that searching for players to warm up with fails (maybe no one is in the queue). I'd rather wish to start the mode with bots and get them replaced with real players afterwards to be honest. I know, the Single Bot Match mode exists, but the Warm Up map is really more convenient to practice aiming.

*EDIT:* I may add, that stucked doesn't mean "freezed" at this situation.

UPDATE: Today's maintenance didn't really affect the bug error. Additionally now when you try to enter the Warm Up Mode , sometimes it kicks you back to the "Server Selection" section