title: Why did my TeamCity build stop working?
body: <p>I have a TeamCity build configuration that has been working fine until recently. Suddenly, there is a build stuck in the queue that says it is not compatible with any agents. The reason given is:</p>
  
  <blockquote>
    <p>Implicit requirements: teamcity.build.branch defined in Parameter: BuildFormatSpecification</p>
  </blockquote>
  
  <p>My BuildFormatSpecification parameter is defined thus:</p>
  
  <blockquote>
    <p>%MajorVersion%.%MinorVersion%.%PatchVersion%-%teamcity.build.branch%</p>
  </blockquote>
  
  <p>That in turn is used in the Build Number Format field along with a build counter, like this:</p>
  
  <blockquote>
    <p>%BuildFormatSpecification%.%sharedBuildNumber.id4%</p>
  </blockquote>
  
  <p>The idea is that the build number comes out like "1.0.0-develop.22" and includes the Git branch being built. This follows the rules for Semantic Versioning. This scheme has worked for me over a number of projects, but suddenly this one build is stuck and I can't figure out why.</p>
  
  <p>Any ideas?</p>