This it the MANDATORY release. ALL nodes need to update. Mainnet has been rolled back to block 5481020.
After updating, you will need to manually roll back the node:
curl -H 'x-api-key: <your API key here>' \
-H 'content-type: application/json' \
-d '{"rollbackTo":5481020,"returnTransactionsToUtx":false}' http://localhost:6869/debug/rollback
Block 79hmk7xT74PoZpa7G2DG68uhfNegEpu4eBT4mSfm4B9 is at height 5481021 on the correct chain.