diff --git a/docs/reference/supported-technologies.md b/docs/reference/supported-technologies.md
index d60291a0b..b31536390 100644
--- a/docs/reference/supported-technologies.md
+++ b/docs/reference/supported-technologies.md
@@ -111,6 +111,10 @@ We support these Starlette versions:
 
 Any FastAPI version which uses a supported Starlette version should also be supported.
 
+::::{note}
+`fastapi>=0.137` requires `elastic-apm>=6.26.2`.
+::::
+
 
 ### GRPC [supported-grpc]
 
diff --git a/docs/release-notes/known-issues.md b/docs/release-notes/known-issues.md
index 4972fdbc9..b94612e7d 100644
--- a/docs/release-notes/known-issues.md
+++ b/docs/release-notes/known-issues.md
@@ -26,4 +26,16 @@ Known issues are significant defects or limitations that may impact your impleme
 
 :::
 
-_No known issues_
\ No newline at end of file
+:::{dropdown} 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 [{{product.apm-agent-python}} 6.26.2](index.md#elastic-apm-python-agent-6262-release-notes).
+:::
\ No newline at end of file