--- title: Elastic APM Python Agent known issues description: Known issues are significant defects or limitations that may impact your implementation. These issues are actively being worked on and will be addressed... url: https://www.elastic.co/elastic/docs-builder/docs/3558/release-notes/apm/agents/python/known-issues products: - APM Agent - APM Python Agent applies_to: - Serverless Observability projects: Generally available - Elastic Stack: Generally available - Application Performance Monitoring Agent for Python: Generally available --- # Elastic APM Python Agent known issues Known issues are significant defects or limitations that may impact your implementation. These issues are actively being worked on and will be addressed in a future release. Review the Elastic APM Python Agent known issues to help you make informed decisions, such as upgrading to a new version. **Details**On 06/19/2026, a known issue was discovered that FastAPI 0.137 changed how included routers are represented internally, introducing `_IncludedRouter` wrapper objects that do not expose a `.path` attribute. The ElasticAPM Starlette/FastAPI middleware accessed `.path` unconditionally, causing an `AttributeError` and a 500 response on every HTTP request when using `app.include_router()`.**Workaround**Pin `fastapi<0.137` until you can upgrade to `elastic-apm>=6.26.2`.**Resolved**On 06/22/2026, this issue was resolved in [APM Python Agent 6.26.2](/elastic/docs-builder/docs/3558/release-notes/apm/agents/python#elastic-apm-python-agent-6262-release-notes).