AttributeError: 'FastAPI' object has no attribute 'debug' Error

[itayG98]

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Example Code

debug = self._debug

Description

Running a Fast API crushes with Attribute error
venv\Lib\site-packages\fastapi\applications.py", line 153, in build_middleware_stack
debug = self.debug
^^^^^^^^^^
AttributeError: 'FastAPI' object has no attribute 'debug'

Operating System

Windows

Operating System Details

No response

FastAPI Version

0.90.0

Python Version

3.11

Additional Context

I've got back in a personal project and ran my server however it crashed with that error
I see that in the build_middleware_stack method it uses the _debug attribute the wrong way

fastapi/fastapi/applications.py

Line 153 in 148bcf5

debug = self.debug

This code should be :

 debug = self._debug

[Jorricks]

Exactly the same error here with FastAPI==0.89.1

Requirements list

$ pip3 freeze
anyio==3.6.2
attrs==22.2.0
certifi==2022.12.7
charset-normalizer==3.0.1
click==8.1.3
duty-board==0.1.0
fastapi==0.89.1
greenlet==2.0.2
h11==0.14.0
httpcore==0.14.7
httpx==0.22.0
ical-library==0.2.1
idna==3.4
itsdangerous==2.1.2
Jinja2==3.1.2
ldap3==2.9.1
MarkupSafe==2.1.2
pendulum==2.1.2
Pillow==9.4.0
psycopg2-binary==2.9.5
pyasn1==0.4.8
pydantic==1.10.4
python-dateutil==2.8.2
python-multipart==0.0.5
pytz==2022.7.1
pytz-deprecation-shim==0.1.0.post0
pytzdata==2020.1
PyYAML==6.0
requests==2.28.2
rfc3986==1.5.0
six==1.16.0
sniffio==1.3.0
sqladmin==0.8.0
SQLAlchemy==1.4.46
starlette==0.24.0
typing-extensions==4.4.0
tzdata==2022.7
tzlocal==4.2
urllib3==1.26.14
uvicorn==0.20.0
WTForms==3.0.1

Stack trace

Traceback (most recent call last):
  File "/home/bigdata/venv/bin/uvicorn", line 8, in <module>
    sys.exit(main())
  File "/home/bigdata/venv/lib64/python3.9/site-packages/click/core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
  File "/home/bigdata/venv/lib64/python3.9/site-packages/click/core.py", line 1055, in main
    rv = self.invoke(ctx)
  File "/home/bigdata/venv/lib64/python3.9/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/home/bigdata/venv/lib64/python3.9/site-packages/click/core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "/home/bigdata/venv/lib64/python3.9/site-packages/uvicorn/main.py", line 404, in main
    run(
  File "/home/bigdata/venv/lib64/python3.9/site-packages/uvicorn/main.py", line 569, in run
    server.run()
  File "/home/bigdata/venv/lib64/python3.9/site-packages/uvicorn/server.py", line 60, in run
    return asyncio.run(self.serve(sockets=sockets))
  File "/usr/lib64/python3.9/asyncio/runners.py", line 44, in run
    return loop.run_until_complete(main)
  File "/usr/lib64/python3.9/asyncio/base_events.py", line 647, in run_until_complete
    return future.result()
  File "/home/bigdata/venv/lib64/python3.9/site-packages/uvicorn/server.py", line 67, in serve
    config.load()
  File "/home/bigdata/venv/lib64/python3.9/site-packages/uvicorn/config.py", line 477, in load
    self.loaded_app = import_from_string(self.app)
  File "/home/bigdata/venv/lib64/python3.9/site-packages/uvicorn/importer.py", line 21, in import_from_string
    module = importlib.import_module(module_str)
  File "/usr/lib64/python3.9/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1030, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1007, in _find_and_load
  File "<frozen importlib._bootstrap>", line 986, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 680, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 850, in exec_module
  File "<frozen importlib._bootstrap>", line 228, in _call_with_frames_removed
  File "/home/bigdata/venv/lib64/python3.9/site-packages/duty_board/server.py", line 33, in <module>
    app = FastAPI()
  File "/home/bigdata/venv/lib64/python3.9/site-packages/fastapi/applications.py", line 146, in __init__
    self.middleware_stack: ASGIApp = self.build_middleware_stack()
  File "/home/bigdata/venv/lib64/python3.9/site-packages/fastapi/applications.py", line 152, in build_middleware_stack
    debug = self.debug
AttributeError: 'FastAPI' object has no attribute 'debug'

[Kludex]

encode/starlette#2017

Edit by @tiangolo: You shouldn't pin Starlette: https://fastapi.tiangolo.com/deployment/versions/#about-starlette

[itayG98]

Ohh i see
i downgraded to starlette==0.22.0

thanks!

[Kludex]

No, that's not what you should do.

Install FastAPI without caring about Starlette, it will install the right version.

[tiangolo]

Thanks @Kludex! Yep, you shouldn't pin Starlette: https://fastapi.tiangolo.com/deployment/versions/#about-starlette

[Jorricks]

Yes in my case, starlette was installed through another app first that took the latest version. Now that I am back on the earlier starlette version, it works again indeed. Thanks!

[itayG98]

Thanks a lot!
I will Un-pin the starlette
now it works fine :)

[KevinKeyssx]

I solved it by updating to the most current version of Fastapi 0.93.0 and it already lifts my application