Here are some common issues that you may encounter when configuring and using Cover Pipeline for GitHub.


Diffblue Cover performs a number of checks before, during, and after creating unit tests. Cover can generate a range of output codes during these checks to provide general information and highlight any issues. These codes and associated messages are output during the run, visible in the job output, and saved to the log files. See Output Codes for details.

For general Diffblue Cover issues, see the Cover CLI Troubleshooting topic.

Diffblue license issues

License issues are reported using L - License Codes. Common issues include:

  • L005 - The license has expired - Update your license key (see Configuration) and/or contact Diffblue Support for assistance.

  • L009 - License key not found - Make sure you've entered the correct license key and in the format provided (see Configuration).

Access token issues

Access token issues are reported using the E120 - Git command failed output code (see E - Environment Codes). For example:

  • Access token with incorrect permissions. In this case, check that the access token has correct permissions for the project - see Configuration.

INFO Pushing: 2023.11.02-RC2
ERROR E120: Git command failed
The following git command failed with an exit code of 128:
/usr/bin/git push origin HEAD:2023.11.02-RC2
Beginning of output
> remote: You are not allowed to push code to this project.
> fatal: unable to access '':
  The requested URL returned error: 403
  • A mismatch of the access token name can lead to a Git error. GitHub requires the access token name used in the Diffblue Cover Action to match the name of the access token in GitHub. Check and update your access token name as needed - see Configuration.

Diffblue Cover Docker issues

The Diffblue Cover docker image to use as part of your project pipeline is specified in your workflow YAML file (see Configuration). Tag variations are provided for each supported JDK version (see for details). An error in the naming of the docker image will cause a failure to download the docker file:

To resolve this issue, simply update the docker image name in your workflow YAML file.

No unit test changes

If no tests are created, updated, or removed as part of your merge request, you may have selected the Diffblue Cover: Skip label in the pull request. This label is used to mark a pull request as requiring no tests to be written. See Configuration.

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