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🚸 Improve tracebacks by adding endpoint metadata #14306
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Merged
tiangolo
merged 17 commits into
fastapi:master
from
savannahostrowski:improved_tracebacks
Dec 6, 2025
Merged
🚸 Improve tracebacks by adding endpoint metadata #14306
tiangolo
merged 17 commits into
fastapi:master
from
savannahostrowski:improved_tracebacks
Dec 6, 2025
+289
−16
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…owski/fastapi into improved_tracebacks
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YuriiMotov
reviewed
Nov 7, 2025
tiangolo
approved these changes
Dec 6, 2025
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This is amazing, thank you! 🤩 🙌
It will be available in FastAPI 0.124.0, released in the next few hours. 🎉
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Today, when validation errors occur, error messages don't indicate what endpoint caused the problem, which can make debugging difficult.
This PR adds endpoint context metadata to validation error messages to show the filepath (clickable in IDEs!) and line number, function name and HTTP method and route where applicable. The endpoint context is extracted once per endpoint and then cached to avoid any additional performance overhead on subsequent requests. Just to double check, I also ran a rough benchmark (100k requests):
Endpoint context only appears in the exception's string representation (server logs). It is not exposed to clients in HTTP responses. Clients still receive the standard 422 response with validation error details.
Examples
ResponseValidationError
Before:
After:
RequestValidationError
Before:
After:
WebSocketRequestValidationError
Before:
After: