I was getting this error fairly regularly and I did a few things to help alleviate it(I haven't seen it in a few weeks).
1. Moved the game to a separate hard drive.
2. Disabled steam shader cache.
3. Verify files before launching the game.
4. Queue up into a private bot match and make sure the game can get me to lane.
If you encounter this issue again, an idea to quickly remediate it that I haven't been able to test out - maybe try logging out of your steam and logging back in? After a few of us were digging into this issue in another thread, we saw that steam is intentionally blocking updates for a few minutes which means any attempt to verify will stall and not be able to do anything in time to avoid the ban. My theory is logging in and logging out will clear whatever local state is there and hopefully let you verify quicker...