Hello,
Thank you for posting in Q&A forum.
Backup requires some additional disk space on the client computer to create a VSS snapshot. On any volume that is not system reserved, at least 10 percent of available disk space must be free. On a system reserved volume, if the volume size is less than 500 MB, VSS requires 32 MB of free space to create a snapshot; if the volume is 500 MB or greater, VSS requires 320 MB of free space.
If the backup error still occurs even though the above requirements are met, I suggest you refer to the following link for troubleshooting:
I hope the information above is helpful.
Best regards
Zunhui
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