VSS Error

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-V?Virtual?Machine\SQL02". Snapshot technology used: Microsoft Volume Shadow Copy Service (VSS). A virtual machine snapshot could not be created. Use the Event Viewer on the Hyper-V host to identify the cause. If the virtual machine is not properly configured, it may be necessary to use the Event Viewer in the virtual machine to identify the cause. 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?