VSS Error

[FORGIVEN]

BE 15 backing up hyper-v host (2012 R2 core) and guests (exchange 2013, sql 2014, SCOM 2012 R2, remote desktop services 2012 R2 and a SLES 12). I have the agent 14.x installed on the host and all guests. On this particular backup job, i get an error in the job log:

V-79-40960-38521 - Snapshot Technology: Initialization failure on: "VRTSRV::\\2012R2Core0.electrichendrix.com\Hyper-...A virtual machine snapshot could not be created.  Use the Event Viewer on the Hyper-V host to identi...The following volumes are dependent on resource: "C:" .
The snapshot technology used by VSS for volume C: - Microsoft Software Shadow Copy provider 1.0 (Version 1.0.0.7).

If i follow the link from that kob error and run VSSADMIN LIST WRITERS:

Writer name: 'SqlServerWriter'
   Writer Id: {a65faa63-5ea8-4ebc-9dbd-a0c4db26912a}
   Writer Instance Id: {d3c1073a-aa20-4e60-b197-f7508205b110}
   State: [8] Failed
   Last error: Inconsistent shadow copy 

and VSSADMIN LIST PROVIDERS comes back fine. Here is the error from the event log on the vm host:

event id 18012:

Checkpoint operation for 'SQL02' failed. (Virtual machine ID 39C03464-FD21-4319-BF17-7EF6FA7452F6 

then id 10150:

Could not create backup checkpoint for virtual machine 'SQL02': The shadow-copy set only contains only a subset of the volumes needed to correctly backup the selected components of the writer. (0x800423F0). (Virtual machine ID 39C03464-FD21-4319-BF17-7EF6FA7452F6) 

then id 10172:

VSS writers inside virtual machine 'SQL02' failed to perform BackupComplete to its shadow copy (VSS snapshot) set: The shadow-copy set only contains only a subset of the volumes needed to correctly backup the selected components of the writer. (0x800423F0). (Virtual machine ID 39C03464-FD21-4319-BF17-7EF6FA7452F6) 

then id 16010:

The operation failed. 

then id 10172:

VSS writers inside virtual machine 'SQL02' failed to perform BackupComplete to its shadow copy (VSS snapshot) set: Catastrophic failure (0x8000FFFF). (Virtual machine ID 39C03464-FD21-4319-BF17-7EF6FA7452F6) 

Anyone have any ideas how to get this job backing up again? 

[FORGIVEN]

I did some windows updates and rebooted the vm with the writer error. Upon logging back in after the reboot, i ran vssadmin list writers and none were in an error state. The backup is suppose to run tonight so i will report back if it fails or succeeds.