Self-hosted build agent cannot connect to Azure DevOps Services, SSL connection could not be established

Question

Hello over the weekend my self-hosted build agent lost connection to the DevOps Services. Not completely but I am getting connection errors on almost all of my builds. my builds are failing with the error:

ERR Agent] System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host..

From the Agent diagnostic logs.

I tried re-installing the Agent but this is not possible either as I get the exact same error when I try to run "config.cmd remove"

I tried adding --sslskipcertvalidation but this does not seem to work with the remove command. I tried to remove the old from the services, but it will not remove from the agent machine as I cannot complete the "config.cmd remove" process.

No clue why I am getting these connection errors all of a sudden. (I am on the Basic plan) Does not seem to be relating to any current reported Azure outages (2021-04-12).

Many thanks for any advice.

Answer 1

I ended up installing the agent again in a separate folder from the old agent. Likely the issue was that the old agent was installed with the url [org.name].visualstudio.com I guess there is now some SSL certificate issue on the old url. I installed the new agent with the dev.azure.com/[org.name] url and this solved all of my issues.