We had issues, along with every other witness yesterday, but are back up and running now.

The issue was that new code (HF20) was not kept under wraps and was let loose (not the fault of the witnesses who upgraded really) to test, but for some reason started running without 'the gate' stopping this from happening.

A post was up-voted after 6.5 days (allowable in the new code), and the node mining the block (on v19) didn't know what to do - hence a fork.

All witnesses are moving back to 19.x while this error is fixed, and we should hopefully be able to try again soon.

Cheers!