Firstly apologies if this is in the wrong feed.

My Windows Server 2012 system uses Windows Server Backup along with a QNAP TS-412 device with 8TB of storage. For the last few weeks I have been having issues where the schedule "completes with warnings" where the warning is that the system state has not been backed up and the only error message I get is "Copy of the files failed. Detailed error: The specified path is invalid".

My initial thought was that the QNAP was shutting itself down before the backup had time to finish (the previous Tech before me had set it up to power on half an hour before the scheduled start time - 6.30pm for a 7pm start - and then shutdown at 7am). I tried extending that time to 9am but I was still met with these warnings. Upon further exploration, WSB (Windows Server Backup) tells me I am only using 1.8TB of space but if I look on the web console for the QNAP, it tells me I only have 17GB of space remaining.

Any thoughts as to what I can do to rectify these errors? If there is anymore information needed then just ask