Avamar: SQL backup operations randomly stop responding leaving avsql and avtar processes stuck

Randomly during Avamar backup a customer sees backup stopped responding requiring manual intervention.
This behavior is mostly seen during backups of large Databases and multi-streaming enabled.

<flag type="pulldown" pidnum="3006" value="4" name="max-parallel" />
    <flag type="pulldown" pidnum="3006" value="1024" name="min-snapup-size" /> 

The same server backup will run successfully next time and may not exhibit these stop responding symptoms again for a while.

During the stop responding, the data processing stops until the Virtual Backup Device Interface (VDI) connection times out as per "vditransfertimeoutsecs" settings. In customer case, it was set to 3 hrs and time-out for avsql_t3 thread in the excerpt below:
 

2019-11-05 19:43:27 avsql Info <42988>: VDC_Complete is not supported by VDI.
2019-11-05 19:43:27 avsql Error <6478>: VDS::Getconfig failed with 'The api was waiting and the timeout interval had elapsed'
2019-11-05 19:43:27 avsql Error <6479>: Timed out. Was Microsoft SQLServer running?
2019/11/06-00:43:27.75200 [avsql_t3] Canceling avtar sub-process ... 

Here the avsql_t3 thread is stuck after calling GetConfiguration of SQL VDI function.

There is a software glitch in the GetConfiguration() component of the Microsoft SQL VDI API/function that Avamar Plugin uses.

The software glitch is under investigation by Avamar and Microsoft developers. 

Contact Avamar support for the latest update.