VSS writers re registration
Sometimes few writers are not listed when running command vssadmin list writers due to vss writers corruption, this can be resolved with these below troubleshooting steps.
Backup is failing due to corrupted VSS writers or Re register VSS writers.
Event ID: 12302
Locate and then click the following registry subkey:
Delete this sub key (Subscriptions)
Open Service management console services.msc and restart below services.
COM+ Event System
COM+ System Application
Microsoft Software Shadow Copy Provider
Volume Shadow Copy
Re-register VSS writers with the below commands.
cd /d %windir%\system32
net stop vss
net stop swprv
regsvr32 /i eventcls.dll
regsvr32 /i swprv.dll
Note The last command may not run successfully.
Now run vssadmin list writers command to Confirm that the VSS writers are now listed.