First of all, if you use xcpretty to format the output try a build without it (if you use the Xcode Test Step you can set xcodebuild as the “Output Tool” option/input to not to format the log produced by xcodebuild). The cause is: xcpretty sometimes omits the error message in it’s output.

If you don’t use our Xcode Test Step to run your UI Test you should try to run it with our Xcode Test Step. We always try to improve the reliability of the Step, implementing known workarounds for common issues.

If you use our Xcode Test Step: make sure you use the latest version, as it might include additional workarounds / fixes.

Try another Xcode version, there are issues which are present in one Xcode version but not in another one.

Make sure your desired Xcode scheme is shared. Don’t forget to commit and push the changes if you just enabled it.

It might also be a project configuration issue in your Xcode project, a code issue in your tests, or a multi-threading issue in your code.

We received reports that this might also be caused by Code Coverage report generation, you can disable the Generate code coverage files? option of the Xcode Test Step to not to generate Code Coverage files.