This helped:

Open the Command Prompt or the Windows PowerShell.

Navigate to your Stable Diffusion folder using the cd command. For example, if your Stable Diffusion folder is located at C:\artificial-intelligence-tools\stable-diffusion-webui, you would run the following command:

cd C:\artificial-intelligence-tools\stable-diffusion-webui
.\venv\Scripts\Activate.bat
pip install fastapi==0.90.1
deactivate

Close cmd or powershell
Start Stable Diffusion as you normally would.

we have another issue for it here - #7714

.\venv\Scripts\python.exe -m pip install --upgrade fastapi==0.90.1

.\venv\Scripts\python.exe -m pip install --upgrade fastapi==0.90.1

My problems is solved with your method, thank you very much.