VS Code Local Port Forwarding Error 502 – "This page isn’t working"

[ejajahmad]

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I'm trying to use VS Code local port forwarding to forward port 3000, but when I try to access the generated URL (v0jw1fjz-3000.inc1.devtunnels.ms), I get the following error:

This page isn’t working v0jw1fjz-3000.inc1.devtunnels.ms is currently unable to handle this request. HTTP ERROR 502

What I've Tried:

• Verified my local server is running on port 3000 (npm run dev for a Next.js app).
• Restarted VS Code and my PC but the issue persists.
• Manually stopped and restarted port forwarding via the VS Code Command Palette.
• Tried a different port (3001, 8080) but got the same issue.

[Bushra-Butt-17]

Hey! It sounds like you’re running into a pretty common issue with VS Code’s Dev Tunnels and local port forwarding. That HTTP 502 error basically means that the tunnel was created successfully, but it couldn’t connect to your local server. Let’s break down some things you can try to fix this!

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✅ Step 1: Check Your Local Server

First things first, make sure your server is actually running and listening on port 3000. You can check this by opening your browser and visiting:

http://localhost:3000

If that works, great! It means your server is up and running locally. If not, double-check that you started your app correctly (e.g., npm run dev for a Next.js app).

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🔄 Step 2: Restart Port Forwarding

Sometimes VS Code’s port forwarding just needs a little kick to get going again. Try manually stopping and restarting it:

1. Open the Command Palette (Ctrl + Shift + P).
2. Type "Dev: Forward Port" and select it.
3. Enter port 3000 and make sure the URL it generates matches the one you’re trying to access.

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🚀 Step 3: Check Logs and Output

You can also check the output for any errors or warnings:

1. Go to View -> Output in VS Code.
2. Choose "Dev Tunnels" from the dropdown list.
3. Look for any errors or messages that could point to what’s going wrong.

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🔧 Step 4: Make Sure Port 3000 Is Free

Sometimes, another app might be hogging that port. You can check what’s using it:

On Windows:

netstat -ano | findstr :3000

If you find a process using it, kill it with:

taskkill /PID <PID> /F

On Mac/Linux:

lsof -i :3000

Kill the process with:

kill -9 <PID>

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🔥 Step 5: Check Your Firewall/Antivirus

Your firewall or antivirus might be blocking the connection. Try temporarily disabling them and see if that makes a difference. You can also manually allow port 3000 through your firewall.

---

🔄 Step 6: Restart Networking Services

Sometimes just restarting your networking services can do the trick:

• On Windows, restart the Network Location Awareness service.
• On Mac/Linux, restarting your network interface or just rebooting can help.

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💡 Step 7: Try a Different Port

To see if the problem is specific to port 3000, try forwarding a different port (like 3001 or 8080). You might also want to run a quick test with a basic HTTP server to rule out any app-specific issues:

python -m http.server 3000

If that works with the tunnel, it might be something in your app’s configuration.

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📝 Final Tips:

• Make sure your server is configured to accept connections from all interfaces, not just localhost. Sometimes apps only bind to 127.0.0.1, which can block external access.
• If nothing works, it might be an issue with VS Code’s Dev Tunnels itself. Consider updating VS Code and the Dev Tunnels extension or reinstalling them altogether.

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[Acosta-Armando]

I had the same problem and it was solved by right-clicking on the forwarded port and in "change port protocol" I selected http, I still create the tunnel with https so I assume it is the protocol of my local server that specifies that option.