Managed to resolve.
I have two external drives connected via powered hub direct into the MyCloud - these were called Backup_1 and Backup_2
After the firmware upgrade, the same two folders existed, but were joined by two others “Backup_1-1” and “Backup_2-2”
None were accessible, and the error codes shown were as above.
In the end, I removed the drives and all traces of the share. Ran chkdsk through the laptop (which picked up a fault on one drive), and the reapplied the firmware. Once done, I connected both drives and was back as it should be.
Question though:why the error?
