Introduction
For users using the GitLab VCS integration, you may sometimes encounter an Error Fetching Config error or the message We received an unauthorized error response from GitLab while trying to read config from your GitLab project. When encountering this issue new pipelines will fail to run.
This is because the config-source token used to retrieve the CircleCI configuration file is rejected by GitLab.
Solution
To resolve this error, please follow the steps below to re-create the triggers and configuration source:
Navigate to Project Settings
Under the "Triggers" section, delete all the triggers associated with the problematic configuration first.
Under the "Configuration" section, delete the problematic configuration source after the triggers.
Once the triggers and configuration source have been successfully deleted, recreate the triggers and configuration source
Push a new commit to verify a pipeline triggers
Outcome
Once the Triggers and Configuration Source have been deleted and re-created, please trigger the pipeline by pushing a new commit and if you are still encountering issues, please contact the CircleCI Support Team by submitting a request.