Elastic APM Python Agent known issues
Elastic Cloud Serverless projects are autoscaled environments, fully managed by Elastic and available on Elastic Cloud. Availability This functionality is generally available and ready for production usage. The Elastic Stack includes Elastic's core products such as Elasticsearch, Kibana, Logstash, and Beats. Availability This functionality is generally available and ready for production usage. Unless stated otherwise on the page, this functionality is available when your Elastic Stack is deployed on Elastic Cloud Hosted, Elastic Cloud Enterprise, Elastic Cloud on Kubernetes, and self-managed environments. This documentation corresponds to the latest patch available for each minor version. If you're not using the latest patch, check the release notes for changes. The Elastic APM Python agent enables you to trace the execution of operations in your Python applications, sending performance metrics and errors to the Elastic APM Server. Availability This functionality is generally available and ready for production usage. This documentation corresponds to the latest patch available for each minor version. If you're not using the latest patch, check the release notes for changes.
Serverless Observability
Generally available
Stack
Generally available
APM Agent Python
Generally available
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.
FastAPI 0.137+ causes 500 errors on every request
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.