When I try to join a friend's game via Steam, it says "You have been banned from the current session"

This only started happening after the recent patch (7.06, came out about 10 minutes ago).

He of course hasn't banned me, but we can't join each others' games. How can we fix this?

Solution 1:

This will be fixed in a hotfix tomorrow.

• Fixed Private Match joining bug. Temporary workaround for 7.06: If you are experiencing issues joining a friends match or friend joining yours, toggle the Show/Hide Match button in the pause menu

Solution 2:

Sorry for answering my own question so quickly, but a lot of people are having this issue right now.

To solve, have the host hit escape and click Show match in the upper-right.

I don't know why they would make the default setting "open to the public but closed to friend's list"...