Calculating Space Remaining
Something occured to me based on experience in using another disk imaging backup software: Norton Ghost.
When Ghost would hang in a similar fashion, the error message would indicate that there is insufficient HD space on the drive being backed up to create the image that will be written to the backup device. I had, in those days, a 1 Tb drive that was at 95% capacity. Ghost would go into an endless loop and eventually error out, producing an error message and shutting down.
I am backing up a 2 Tb drive with 1.36 Gb of used space. Where does Acronis "hit the wall" and not be able to create the image for processing to backup? Are there settings in the Acronis setup that would circumnavigate this up to a point?
Others have been stuck here due to a failing / bad disk or one with bad sectors - may try running chkdsk on the drive or using a free third party tool like hard disk sentinel which will not only check the C: drive sectors, but sectors on the hidden paritions as well.
Alternatively, it may be as simple as turning off VSS for a specific backup and letting Acronis fall back on it's only proprietary backup method which was the default in 2014 and earlier, but now is the secondary method as they are using Windows VSS by default first.
https://forum.acronis.com/forum/116164#comment-346710
It is also possible to disable VSS usage for a particular backup task without touching Windows VSS service itself:
1) open the folder where your backups settings are saved: C:\ProgramData\Acronis\TrueImageHome\Scripts
2) each file there stores settings for particular backup job. Open files one-by-one in Notepad, or open latest modified file (if you have just modified your task), until you find the one that has backup name on 5th line, e.g. MyBackups
3) click Edit - Replace and replace use_vss="true" with use_vss="false"
4) save changes and close the file
Thanks,
Slava