Backup Failing due to Failed VSS Writer

Hi!

Our Exchange 2013 Backup is failing due to a vss writer failure. The message in vss writer status is:

Writer name: 'MSMQ Writer (MSMQ)'
   Writer Id: {7e47b561-971a-46e6-96b9-696eeaa53b2a}
   Writer Instance Id: {3dbfb560-3e45-4dbe-8284-021982a8126f}
   State: [7] Failed
   Last error: Timed out

Exchange Version is Version 15.0 (Build 516.32)

If it needs to be updated to fix this problem then can we install the newest update which is CU6 directly without installing the previous updated which were released before CU6?

What safety measures we should take before installing CU6 as the backup is not working?

Thanks.