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!