python runtime_error ai_generated true

fastapi.exceptions.HTTPException: 404: Not Found

ID: python/fastapi-http-exception-404-not-found

Also available as: JSON · Markdown · 中文
80%Fix Rate
88%Confidence
0Evidence
2024-05-20First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

Requested URL path does not match any defined route in the FastAPI application.

generic

中文

请求的 URL 路径与 FastAPI 应用中定义的任何路由不匹配。

Workarounds

  1. 95% success Check and correct the route definition 
    @app.get('/items/{item_id}')
async def read_item(item_id: int):
    return {'item_id': item_id}
# Access /items/123, not /items/
  2. 90% success Add a custom 404 handler for better debugging 
    @app.exception_handler(404)
async def not_found_handler(request, exc):
    return JSONResponse(status_code=404, content={'message': 'Route not found'})

Dead Ends

Common approaches that don't work:

  1. Adding a catch-all route that returns 200 60% fail

    Masks real errors and may cause unintended behavior.

  2. Assuming trailing slash mismatch 50% fail

    FastAPI by default does not redirect, so /users and /users/ are different.