2020-06-22 11:16 AEST by Arthur Barrett - Bug 6038 fixed a lot of the 'switch to user failed ... ' issues that CVSMANAGER_USER was a temporary fix for.

In future releasess (see bug 7429) this will be fixed in the installer

But we could detect on the server if pserver/sserver and runasuser=clientuser and service is 
CVSMANAGER_USER and the error is  'switch to user failed ... ' and give a helpful hint:

  this error can usually be fixed by using the 'services' 
  control panel on the server and set the 'high performance
  server service' on the server to run as SYSTEM