Managed Backup Job fails with "Error Unknown invoker method: 2757"

Challenge

A Backup Job using Veeam Agent for Windows which is managed by a Veeam Backup & Replication server fails with the following error:
 

Failed to start backup job Error: Unknown invoker method: 2757

Cause

This issue occurs when the version of Veeam Agent for Windows running on the Windows computer being backed up is incompatible with the version of Veeam Backup & Replication running on the management server.

This specifically occurs when the version of Veeam Agent for Windows installed in the machine is v3.0.2.x and the version of Veeam Backup & Replication on the management server is not 9.5 U4b (9.5.4.2866).

Solution

To resolve this issue the installation of Veeam Backup & Replication on the management server must be brought up to a compatible version by install Update 4b for Veeam Backup & Replication v9.5.

The Veeam Backup & Replication v9.5 Update 4b release notes and down can be found here: https://www.veeam.com/kb2970