Code that passes locally but fails in CI: common non-code causes

Developers often find their tests passing on their own machines yet failing in continuous integration, even without any code changes. One frequent cause is an unbounded dependency range, where a newly published library version is automatically accepted and breaks the build. Differences in linter versions, Python interpreters, or packages installed only locally can also produce inconsistent results. Test files that exist on a developer's disk but are excluded by .gitignore will be missing in CI and cause failures. The suggested approach is to reproduce the failure locally in a clean environment and compare versions before assuming the CI system is at fault.