## Problem to Solve When a GitLab CI configuration includes a remote file from a private project, the error message is misleading and doesn't clearly explain the actual issue. In the documentation, we mention that: https://docs.gitlab.com/ci/yaml/#includeremote > A public URL accessible by an HTTP/HTTPS GET request: > Authentication with the remote URL is not supported. ### Current Behavior Users see a confusing YAML parsing error: ``` This GitLab CI configuration is invalid: mapping values are not allowed in this context at line 17 column 45 ``` ### Expected Behavior The error message should clearly state: - The remote URL is not accessible - Authentication is not supported for remote includes - The file must be publicly accessible via HTTP/HTTPS - Suggest alternatives (use `include:local` or make the project public/internal) ### Root Cause According to the documentation (https://docs.gitlab.com/ci/yaml/#includeremote): > A public URL accessible by an HTTP/HTTPS GET request. Authentication with the remote URL is not supported. When GitLab tries to fetch a remote file from a private project, it receives a 401/403 response, but instead of reporting this clearly, it returns a generic YAML parsing error that misleads users into thinking their configuration syntax is wrong. ### Example Scenario 1. User has a private project with CI templates: `https://gitlab.com/group/project/template-1.yml` 2. User tries to include it in another project: ```yaml include: remote: https://gitlab.com/group/project/.gitlab-ci.yml ``` 3. GitLab returns: `mapping values are not allowed in this context at line 17 column 45`