More help about database disk image is malformed

You could try to fix it by following these instructions:

If it doesn’t work, a node can still be recovered even if some databases were to be lost: here is how they can be recreated:

In last resort if everything else fails, deleting all database files should work, but you would lose all statistics for current month, and possibly some of your earnings for current month also, but at least the node would be “saved”.