Connect XAML Build Controller to Azure DevOps

Recently I've run into the situation where I needed to configure good old XAML build controller to connect to Azure DevOps, but my attempts kept failing. When I start the build service, first starts successfully and then stops with error TF300063. Every single time. Very annoying.

I have tried to troubleshoot the issue. Checked and double checked the permissions. Reset the client cache. Tried some other things, but nothing helped. Then, I've decided for the fun of it to try to connect XAML Build controller using old Azure DevOps/VSTS URL ( instead of new Azure DevOps URL ( And it worked! Hurray!

It appears that because XAML builds are soon to be deprecated feature, XAML build controller feature have not been updated to work with the new URL. They work just fine with the old URL though. So, until you migrate your XAML builds to new builds (and, you really should do that), you can keep using the old Azure DevOps/VSTS URL ( to have your old XAML build controllers working with brand new Azure DevOps.