python auth_error ai_generated true

fastapi.security.OAuth2PasswordRequestForm: 400 Bad Request: Incorrect username or password

ID: python/fastapi-oauth2-password-error

Also available as: JSON · Markdown · 中文
80%Fix Rate
84%Confidence
0Evidence
2024-04-22First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
3.x active — — —

Root Cause

The OAuth2 password flow receives invalid credentials, either because the user doesn't exist or the password hash doesn't match.

generic

中文

OAuth2密码流程收到无效凭据，可能是因为用户不存在或密码哈希不匹配。

Workarounds

  1. 95% success 
    Use passlib and bcrypt: from passlib.context import CryptContext\npwd_context = CryptContext(schemes=['bcrypt'], deprecated='auto')\nif not pwd_context.verify(password, user.hashed_password):\n    raise HTTPException(400)
  2. 90% success 
    Check if the user exists first: user = db.query(User).filter(User.username == username).first()\nif not user:\n    raise HTTPException(400)

Dead Ends

Common approaches that don't work:

  1. 90% fail

    Storing plaintext passwords and comparing directly is insecure and may cause hash mismatches.

  2. 70% fail

    Using the wrong hashing algorithm (e.g., md5) can cause verification failures.