^{Originally posted by oldfielj-ansto October 31, 2025}

First Check

• I added a very descriptive title here.
• I used the GitHub search to find a similar question and didn't find it.
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• I already read and followed all the tutorial in the docs and didn't find an answer.
• I already checked if it is not related to FastAPI but to Pydantic.
• I already checked if it is not related to FastAPI but to Swagger UI.
• I already checked if it is not related to FastAPI but to ReDoc.

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Example Code

from uvicorn import run
from fastapi import FastAPI, Depends
from fastapi.security import OpenIdConnect


_oidc = OpenIdConnect(
    openIdConnectUrl="https://localhost/auth/realms/test/.well-known/openid-configuration",
)

app = FastAPI(
    title="My Application",
    docs_url="/swagger",
    redoc_url="/docs",
    openapi_url="/openapi.json",
    dependencies=(Depends(_oidc),),
)


@app.get("/")
async def hello_world():
    return {"Hello": "World"}


if __name__ == "__main__":
    run(app=app, port=8080)

Description

Under FastAPI 0.120.2

• Run the example code and navigate to http://localhost:8080/swagger
• Notice that the green "Authorize" button is present and user can choose to authenticate a session, padlock icon is also present on root endpoint.
• Calling the endpoint normally without user being authorized, results in expected 403 status.

Under FastAPI 0.120.3

• Run the example code and navigate to http://localhost:8080/swagger
• Notice that the green "Authorize" button is missing and user cannot choose to authenticate a session, padlock icon is also missing on root endpoint.
• Calling the endpoint normally without user being authorized, results in expected 403 status.

As well as testing Depends I have tested with Security to declare the dependency, which results in the same behavior.

What I'd expect is that FastAPI 0.120.3 displays consistent behavior with FastAPI 0.120.2, when defining a security dependency, and that the "Authorize" button and padlock icon on the root endpoint would be displayed in the auto generated Swagger documentation.

It would seem that in 0.120.3, the security section of the generated openapi.json file is omitted.

Under FastAPI 0.120.2

{
  "openapi": "3.1.0",
  "info": {
    "title": "My Application",
    "version": "0.1.0"
  },
  "paths": {
    "/": {
      "get": {
        "summary": "Hello World",
        "operationId": "hello_world__get",
        "responses": {
          "200": {
            "description": "Successful Response",
            "content": {
              "application/json": {
                "schema": {}
              }
            }
          }
        },
        "security": [
          {
            "OpenIdConnect": []
          }
        ]
      }
    }
  },
  "components": {
    "securitySchemes": {
      "OpenIdConnect": {
        "type": "openIdConnect",
        "openIdConnectUrl": "https://localhost/auth/realms/test/.well-known/openid-configuration"
      }
    }
  }
}

Under FastAPI 0.120.3

{
  "openapi": "3.1.0",
  "info": {
    "title": "My Application",
    "version": "0.1.0"
  },
  "paths": {
    "/": {
      "get": {
        "summary": "Hello World",
        "operationId": "hello_world__get",
        "responses": {
          "200": {
            "description": "Successful Response",
            "content": {
              "application/json": {
                "schema": {}
              }
            }
          }
        }
      }
    }
  }
}

If this behavior is expected, and I'm doing something wrong here, please let me know.

Thank you.

Operating System

Linux

Operating System Details

Ubuntu 24.04

FastAPI Version

0.120.3

Pydantic Version

2.12.3

Python Version

Python 3.13.8

Additional Context

Swagger UI - FastAPI 0.120.2

Swagger UI - FastAPI 0.120.3