Lets says Backup runs on your Exchange Server. Where it failed due to Disk space or some connectivity issues
VSS – Volume Shadow Copy Service – is responsible for your Backups on your Exchange Server
To Check for your Available writers you can run the below command in your command prompt
Vssadmin list writers
And some writers may be unstable or in waiting for completion state.
Especially “Microsoft Exchange Writer”
if that is unstable or waiting for completion for a long time , Eventually your Next backup will fail
You can try restarting Microsoft Exchange Information store Service to refresh it
or you can reboot the server
to get the writers back to stable.
If nothing could get your writers to stable state.
As a Last resort you can try Re registering the Vss dlls
Re-registering Vss Dlls
cd /d %windir%\system32 net stop vss net stop swprv regsvr32 /s ole32.dll regsvr32 /s oleaut32.dll regsvr32 /s vss_ps.dll vssvc /register regsvr32 /s /i swprv.dll regsvr32 /s /i eventcls.dll regsvr32 /s es.dll regsvr32 /s stdprov.dll regsvr32 /s vssui.dll regsvr32 /s msxml.dll regsvr32 /s msxml3.dll regsvr32 /s msxml4.dll vssvc /register net start swprv net start vss
It does help in getting the Vss service to function properly