ModuleNotFoundError: No module named 'aiohttp' in ComfyUI
Fix ComfyUI No module named aiohttp errors by installing aiohttp in the active Python environment that starts the server.
If ComfyUI logs ModuleNotFoundError: No module named 'aiohttp', the web server dependency aiohttp is missing from the Python environment that launches ComfyUI.
This can block startup because ComfyUI uses HTTP/WebSocket server components. In the SEO Lab portable repair chain, missing aiohttp appeared after av was installed. Installing aiohttp exposed the next missing package, requests.
Fast answer
For the GitHub Windows portable package:
.\python_embeded\python.exe -s -m pip show aiohttp
.\python_embeded\python.exe -s -m pip install "aiohttp>=3.11.8"
.\python_embeded\python.exe -s -c "import aiohttp; print(aiohttp.__version__)"
.\python_embeded\python.exe -s ComfyUI\main.py --windows-standalone-buildWhat The Log Looks Like
ModuleNotFoundError: No module named 'aiohttp'The traceback may appear before the server reaches Starting server, or while a plugin imports server/API helpers.
Quick Diagnosis
| What You See | Meaning | First Action |
|---|---|---|
No module named 'aiohttp' before server start | Server dependency missing | Install aiohttp in ComfyUI's Python |
| Browser never opens | Startup may be blocked | Repair aiohttp, restart, read the new log |
Error changes to requests | Chain moved forward | Continue with the Requests guide |
| Install succeeds but error remains | Wrong Python was repaired | Verify with ComfyUI's Python |
Step 1: Install aiohttp
Windows portable:
.\python_embeded\python.exe -s -m pip install "aiohttp>=3.11.8"Manual venv:
python -m pip install "aiohttp>=3.11.8"Step 2: Verify The Import
.\python_embeded\python.exe -s -c "import aiohttp; print(aiohttp.__version__)"Manual venv:
python -c "import aiohttp; print(aiohttp.__version__)"Step 3: Restart ComfyUI
.\python_embeded\python.exe -s ComfyUI\main.py --windows-standalone-buildIf the server starts, verify the actual process and port before declaring success. If a new package is missing, continue with that first blocker.
What Not To Do
- do not troubleshoot browser cache before the server dependency imports
- do not install into system Python when ComfyUI uses
python_embeded - do not run a broad requirements command if you are preserving a fragile repaired environment
- do not ignore the next missing package after
aiohttpimports successfully
Related Guides
- No module named 'av' in ComfyUI
- No module named 'requests' in ComfyUI
- ComfyUI Reconnecting error
- Repair ComfyUI Portable Dependencies One Missing Module At A Time
- Fix No module named errors in ComfyUI
Source References
- Windows portable SEO Lab repair, May 18, 2026:
ModuleNotFoundError: No module named 'aiohttp'appeared after AV repair - Same lab
ComfyUI\requirements.txt:aiohttp>=3.11.8 - aiohttp on PyPI
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