Queueing a build fails with poor error message

I tried queue a build and received this error:

root : 'NoneType' object has no attribute 'message'

That wasn’t very helpful, so I added --debug and got something a bit more helpful:

msrest.http_logger : b'{"ClassName":"Microsoft.TeamFoundation.Build.WebApi.BuildRequestValidationFailedException","Messa
ge":"Could not queue the build because there were validation errors or warnings.","Data":null,"InnerException":null,"HelpURL":null,"StackTraceString":null,"RemoteStackTraceString":null,"RemoteStackIndex":0,"ExceptionMethod":null,"HResult":-
2146232832,"Source":null,"WatsonBuckets":null,"m_logException":false,"m_reportException":false,"m_errorCode":0,"m_logLevel":"warning","m_eventId":3000,"ValidationResults":[{"result":"error","message":"An error occurred while loading the YAML build definition. An object ID must be 40 characters long and only have hex digits. Passed in object ID: ."}]}'

Here’s the important part I think:

An error occurred while loading the YAML build definition. An object ID must be 40 characters long and only have hex digits. Passed in object ID: .

I don’t think there is anything wrong with the YAML - builds from the UI work just fine.

[tedchamb]

Filed two bugs last week on the build team for the service. We will be able to provide a more detailed message, once these bugs are addressed.

[lzybkr]

That did help - our default branch is not master, nor do we have such a branch, but specifying the branch worked. Thanks.