We are aware of this and have been working on this for the past hours. Our apologies for the lack of earlier update.

The main issue is that several of the pools had not updated to the new wallet version, and therefore continued mining on the old one. This caused that they continued hashing on the incorrect fork. Under normal circumstances this would not be a problem, however as it turns out, the hashrate on this incorrect fork (which uses the old wallet) is higher than on the correct fork. This causes that the new wallets produce this error.

We are working with the pools and exchanges to resolve this situation immediately, to make sure that everyone is on the same fork. Rest assured that this is being treated as a top priority.

Please note that all plans are still on track as announced - the transition to PoS remains unaffected.

We will post a full update on the block 77777 issue momentarily.