And now we have a problem with 8525 block.

Will continue to have this issue until it's solved with a new wallet release. This is why it's important to have testnet before you start wasting people's hashing power, the monero hardfork 4 days ago literally took 2 minutes, due to good planning, testnet and coordination, no issues at all, more than 2000 nodes updates seamlessly, that's how you run blockchain consensus!
The dev just said in the slack that he'll be implementing the fix in about an hour.