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.
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.