server 500 error, coroutine' object is not iterable, vars() argument must have __dict__ attribute, first time to run nicegui-main/main.py

[HackYardo]

First Check

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• I have checked the FAQs for a similar question and didn't find it.
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Example Code

# at Debian, python is control by apt
mkdir pyve
cd pyve
python3 -m venv .

bin/python -m ensurepip --upgrade
bin/python -m pip install -U NiceGUI

wget 'https://github.com/zauberzeug/nicegui/archive/refs/heads/main.zip'
unzip main.zip

bin/python nicegui-main/main.py

Description

web browser show:

500
Server error
ValueError: [TypeError("'coroutine' object is not iterable"), TypeError('vars() argument must have __dict__ attribute')

terminal show:

NiceGUI ready to go on http://localhost:8080, and http://192.168.8.14:8080
[TypeError("'coroutine' object is not iterable"), TypeError('vars() argument must have __dict__ attribute')]
Traceback (most recent call last):
  File "/home/user/pyve/lib/python3.13/site-packages/fastapi/encoders.py", line 337, in jsonable_encoder
    data = dict(obj)
TypeError: 'coroutine' object is not iterable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/pyve/lib/python3.13/site-packages/fastapi/encoders.py", line 342, in jsonable_encoder
    data = vars(obj)
TypeError: vars() argument must have __dict__ attribute

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/user/pyve/lib/python3.13/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await self.app(scope, receive, _send)
...

NiceGUI Version

3.3.1

Python Version

Python 3.13.5

Browser

Firefox

Operating System

Linux

Additional Context

I find the same issue of fastapi at stackoverflow, people say await perhaps solve the issue, but the script I run is nicegui-main/main.py, there are no any modify.

[evnchn]

Hello @HackYardo

I think it is also #5535

Please downgrade to fastapi 0.123.4

[evnchn]

Or, you can go to 0.123.6

https://github.com/fastapi/fastapi/releases/tag/0.123.6