Are you referring to this previous forum post? We would still need a way to reproduce the error. It’s hard when the issue is transient and possibly environment specific. You could try a sample application in a docker environment maybe if you need multiple servers/clients?
Regarding this issue, again you’ve said it happens sometimes (occasionally). Looking at the code path it looks like there is a possibility that if the network response is null the resolving of the base.Role method in GetServerRole could result in a null reference which we could throw a seperate/specific error or alternate response for, but this will still fail to resolve the server role, so your application would also need to handle that. One option would be wrap that line in a try catch if you can’t upgrade. In the latest version of ServiceStack we are now handling this to return an unknown role, updated in this commit.
Since you are seeing multiple different occasional issues seems to be the root cause will be environmental or network related. What environment are your systems running in? Does your monitoring see any other issues at the same time periods?
It’s a tricky one to track down, but from your previous post there wasn’t anything obvious that you shared that would cause such a problem that we know of.