ComfyUI Reconnecting Error: Fix the Stuck UI

If ComfyUI is stuck on "Reconnecting...", the browser has lost its live connection to the ComfyUI server. Start with the backend terminal, not a reinstall.

In plain English, one of two things usually happened:

• the ComfyUI backend crashed, froze, or restarted
• the browser can no longer keep the websocket connection open

The fastest fix is not reinstalling. It is checking whether the server is still alive, then isolating whether the break is coming from custom nodes, a bad update, or a browser or network block.

Fast Answer

If you searched for "ComfyUI reconnecting error", do these three checks first:

1. Look at the ComfyUI terminal. If it already closed or shows a traceback, treat this as a backend crash.
2. Open http://127.0.0.1:8188 locally before testing a LAN IP, reverse proxy, or remote URL.
3. If reconnecting started after installing or updating nodes, restart once with custom nodes disabled.

If the terminal is gone or you cannot read the log clearly, start with ComfyUI Failed to Fetch Server Logs. If the problem started right after plugin work, also check ComfyUI Dependency Conflicts and ComfyUI Failed to Get Custom Node List.

Quick Diagnosis

Step 1: Check Whether the Server Is Still Alive

Open the ComfyUI terminal window. If the terminal is gone, frozen, or shows a traceback, treat the reconnecting message as a server-side failure.

If the terminal is still running, try opening:

http://127.0.0.1:8188

Use 127.0.0.1 before testing a LAN IP, reverse proxy, or remote address. This separates local ComfyUI problems from network access problems.

If you changed the port, use that port instead of 8188.

Step 2: Read the First Real Error in the Terminal

Do not start with the last line. Scroll up and look for the first serious error:

Traceback (most recent call last):
ModuleNotFoundError
ImportError
CUDA out of memory
RuntimeError
ConnectionResetError

Everything after the first error may be a secondary symptom. For example, a plugin import failure can break the server, and the browser only reports the visible reconnecting state.

The official ComfyUI troubleshooting guide also recommends collecting terminal logs, browser console errors, installed custom nodes, and reproduction steps before reporting a bug.

Step 3: Test Without Custom Nodes

Custom nodes are a common reason ComfyUI starts reconnecting after an update or plugin install.

For a manual install, run:

python main.py --disable-all-custom-nodes

For the Windows portable package, create a copy of your launch batch file and add:

--disable-all-custom-nodes

If ComfyUI works with custom nodes disabled, the core install is probably fine. The problem is likely one custom node, one frontend extension, or a dependency installed by a custom node.

Then narrow it down:

1. Re-enable half of the custom nodes.
2. Restart ComfyUI.
3. If reconnecting returns, the bad node is in that half.
4. Repeat until you find the plugin.

For deeper plugin failures, use How to Fix ComfyUI Plugin Import Failed Errors.

If ComfyUI Manager stopped loading node metadata or plugin lists before the reconnecting loop started, check ComfyUI Failed to Get Custom Node List.

Step 4: Update Frontend and Requirements Together

Some reconnecting problems happen after updating only part of the stack.

If you update ComfyUI with git pull, also update dependencies in the same environment.

If you use the portable package, use the bundled Python, not a random system Python. A common mistake is installing packages into the wrong environment and then wondering why ComfyUI still fails.

For update-related dependency problems, see ComfyUI Dependency Conflicts.

Step 5: Check Browser and Websocket Issues

If the server is alive but the browser keeps reconnecting, check the browser side.

Try:

• reload the page with Ctrl+F5
• use Chrome or Edge with extensions disabled
• open DevTools, then check the Console and Network tabs
• test http://127.0.0.1:8188 instead of a LAN or proxy address
• temporarily disable VPN, proxy, or aggressive antivirus web filtering

ComfyUI relies on a live browser-to-server connection. Browser extensions, proxy tools, remote tunnels, and corporate security software can interrupt that connection even when the Python server is healthy.

If reconnecting happens only in one browser profile, that is a strong sign the backend is probably okay and the break is in the frontend path, not the workflow.

Step 6: Check Port and Firewall Problems

If another app is using port 8188, ComfyUI may fail to bind correctly or you may connect to the wrong process.

On Windows, check the port:

netstat -ano | findstr :8188

If the port is busy, start ComfyUI on another port:

python main.py --port 8189

Then open:

http://127.0.0.1:8189

If you access ComfyUI from another device, make sure the firewall allows the port and that ComfyUI is actually listening on the right network interface.

Step 7: Check GPU or Memory Crashes During Generation

If reconnecting appears only after pressing Queue or while a workflow is running, check for runtime crashes:

• CUDA out of memory
• driver reset
• model architecture mismatch
• custom node execution error
• Python process killed by the OS

Try a smaller workflow:

• lower resolution
• reduce batch size
• close other GPU-heavy apps
• test with the default workflow
• run with --lowvram if your GPU is tight

If the terminal shows CUDA out of memory, see Python Out of Memory in ComfyUI and GPU Compatibility.

Best Next Step by Trigger

When Reinstalling Is the Wrong First Move

Reinstalling can hide the real cause and cost you time if you already have:

• downloaded models
• custom nodes
• working workflows
• project-specific settings
• client or production assets

Use reinstall only after you know whether the problem is core ComfyUI, a custom node, a dependency conflict, or a network or browser issue.

How Wonderful Launcher Helps

Wonderful Launcher is designed for the phase where a ComfyUI environment is no longer a clean install:

• plugins changed dependencies
• startup logs contain multiple failures
• a custom node update broke the frontend
• you need to preserve models and workflows
• you want a clearer recovery path than random shell commands

If reconnecting keeps returning after custom node or dependency work, start with Wonderful Launcher before wiping the environment.

What to Send When Asking for Help

Send these details:

FAQ

Why does ComfyUI keep saying Reconnecting...?

The browser lost the live websocket connection to the ComfyUI backend. The backend may have crashed, a custom node may have broken startup, or the browser/network path may be blocking the connection.

Is failed to fetch server logs the same as reconnecting?

Not exactly. Failed to fetch server logs is often a second symptom after the browser cannot reach the backend log endpoint. If that is the exact message you see, use the Failed to Fetch Server Logs guide after checking the terminal.

Should I use localhost or 127.0.0.1 for ComfyUI?

Use http://127.0.0.1:8188 first when diagnosing. If that works but a LAN IP, reverse proxy, or remote URL fails, the problem is probably network binding, firewall, VPN, proxy, or browser access rather than ComfyUI itself.

Related Guides

• ComfyUI Failed to Fetch Server Logs
• ComfyUI Startup Failed? How to Diagnose and Recover Faster
• How to Fix ComfyUI Plugin Import Failed Errors
• ComfyUI Dependency Conflicts
• ComfyUI Common Issues and Fast Fixes

Source References

• Official ComfyUI troubleshooting overview
• Official custom node troubleshooting guide
• Official ComfyUI update troubleshooting