tiangolo/fastapi · error · HTTPException

X-Token header invalid

Error message

X-Token header invalid

What it means

Non-Annotated variant of error 14: verify_token raises HTTP 400 when X-Token != "fake-super-secret-token". Behavior is identical; only the parameter style differs (x_token: str = Header()).

Source

Thrown at docs_src/dependencies/tutorial006_py310.py:8

from fastapi import Depends, FastAPI, Header, HTTPException

app = FastAPI()


async def verify_token(x_token: str = Header()):
    if x_token != "fake-super-secret-token":
        raise HTTPException(status_code=400, detail="X-Token header invalid")


async def verify_key(x_key: str = Header()):
    if x_key != "fake-super-secret-key":
        raise HTTPException(status_code=400, detail="X-Key header invalid")
    return x_key


@app.get("/items/", dependencies=[Depends(verify_token), Depends(verify_key)])
async def read_items():
    return [{"item": "Foo"}, {"item": "Bar"}]

View on GitHub (pinned to 42a41db11f)

Solutions

1. Send X-Token: fake-super-secret-token.
2. Also send X-Key (see error 17).
3. Centralize the secret in config.

Example fix

# before
client.get("/items/")
# after
client.get("/items/", headers={"X-Token":"fake-super-secret-token","X-Key":"fake-super-secret-key"})

headers = {"X-Token": "fake-super-secret-token", "X-Key": "fake-super-secret-key"}
client.get("/items/", headers=headers)

def has_both_headers(h: dict) -> bool:
    return h.get("X-Token") == "fake-super-secret-token" and h.get("X-Key") == "fake-super-secret-key"

When it happens

Trigger: GET /items/ on the py310 variant without a correct X-Token header.

Common situations: Missing/mismatched token header; secret drift.

Related errors

• X-Token header invalid
• X-Token header invalid
• X-Key header invalid
• X-Key header invalid
• Invalid X-Token header

AI-assisted analysis of tiangolo/fastapi@42a41db11f (2026-08-04). Data as JSON: /data/errors/28c1c9769f86cfce.json. Report an issue: GitHub.