Try possibly deleting chainstate,database,blocks and all files except .conf and wallet?
Could be the chainstate file.
Also I know you tried but ensure you sync from 0 with no banlist.dat present?
Could be an old blockindex stored somewhere.
Ive been able to get all mine up on the new version so something must be grabbing a blockheader from an old online node.
Ensure on your LAN all nodes are updated first also?
Thanks, I'd done all the deletions before that error. There were no others running on my LAN at the time, however restarting it again (but not deleting this time) seems to have got it over the bump, and (fingers crossed) it is working now.
Lets try one more thing, try going into your backups folder and restoring an old wallet file on top of wallet.dat.
Anyone with constant restarts? Try that too.
Otherwise Ill have to continue looking at this in the morning.