[Frank Kruse]

Hi there,

so since we have this happening on 5 different rigs we’ve now at least found a temporary fix. Not actually a fix but a trick that temporarily avoids having to restart till the error hits you the next time.
After the -20021 error happens select across all tracks in the area you’re working in and hit command-option-/ to flatten any automation moves in any of the lanes. (in the empty space where you can do that, or just on the track you're working on) After that PT will allow to play again. So I guess it’s automation related and explains why the error happens in certain areas of the session constantly and never in others.

Must be a certain type of automation moves as the density of automation is definitely very light so it could be a specific type or move that causes this.

Hope this helps.

Frank.