Fix WSAEPROTOTYPE (0X00002739) in 3 Steps

What Is WSAEPROTOTYPE (0X00002739)?

This error pops up when a program tries to create a socket but asks for a protocol type that doesn't match what it's actually using. Think of it like asking for a pizza but specifying the toppings for a salad — the system can't make sense of the mismatch. I've seen this most often with older VPN clients, certain games (especially older MMOs like World of Warcraft Classic), and custom network utilities that get confused after a Windows update. The error code 0X00002739 translates to decimal 10039, which is WSAEPROTOTYPE in Winsock terms.

Here's the thing: you don't need to understand every detail. You just need to fix it. I've trained dozens of techs on this exact issue, and they always start with the simplest possibility first. Let's do the same.

Step 1: The 30-Second Fix — Check Protocol Type in Your App

Most people skip this, but it's the quickest win. The error often means the application itself is coded wrong — it's asking for TCP when it should be UDP, or vice versa. But since you can't rewrite the app, you can check if a setting got flipped.

1. Close the app giving the error.
2. Open its settings or configuration file. Look for anything named "Protocol", "Socket Type", "Connection Type", or "Layer".
3. If you see options like "TCP" vs "UDP" or "IPv4" vs "IPv6", switch to the opposite one.
4. Save and restart the app.

What you should see after this: If the app loads without the error, you're done. If not, move on — the issue is system-level, not app-level.

Step 2: The 5-Minute Fix — Reset Winsock (This Works 80% of the Time)

The real fix for most people is resetting the Winsock catalog. Winsock is the Windows component that manages socket calls. When it gets corrupted — often by a bad VPN install or network driver update — it can pass the wrong protocol type to socket creation. Here's how to reset it cleanly.

1. Press Windows Key + R, type cmd, and press Ctrl+Shift+Enter to run Command Prompt as Administrator.
2. Type this exactly, then press Enter:
   

   netsh winsock reset

3. After the command runs, you'll see a message like "Successfully reset the Winsock Catalog. You must restart the computer to complete the reset."
4. Type this next, then press Enter:
   

   netsh int ip reset

5. You'll see another success message. Close the Command Prompt.
6. Restart your computer.

What you should see after restart: Launch the app again. If the error is gone, you're set. If not, the problem is deeper — likely a corrupted registry key or a third-party driver hooking into Winsock.

My opinion: Skip any "Winsock repair" tools from third parties. They're garbage. The built-in netsh command is all you need.

Step 3: The 15+ Minute Fix — Manual Registry Check and Driver Cleanup

This is for the stubborn cases. If Steps 1 and 2 didn't work, something is permanently misregistered. I've seen this after uninstalling Hamachi, Cisco AnyConnect, or old VPN software that didn't clean up after itself. Here's how to dig into the registry and drivers.

3a. Check the Protocol Registry Key

Windows stores protocol types in the registry. A bad entry here can cause WSAEPROTOTYPE. Let's check it.

1. Press Windows Key + R, type regedit, and press Enter.
2. Go to this path:
   

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\WinSock2\Parameters\Protocol_Catalog9

3. Click on the Protocol_Catalog9 folder. In the right pane, look for entries named Next_Catalog_Entry and check their data — you'll see entries like AF_INET (IPv4), AF_INET6 (IPv6), and protocol types like IPPROTO_TCP or IPPROTO_UDP.
4. If you see an entry that looks out of place — like a protocol type that doesn't match the address family — that's your culprit. Right-click the entry and select Delete.
5. Close Registry Editor and restart your computer.

What you should see after restart: If the error is gone, great. If not, proceed to the driver cleanup.

3b. Remove Problematic Network Drivers

Sometimes a third-party network driver (especially from VPNs, proxy tools, or network filters) hooks into Winsock and corrupts the protocol mapping. Here's how to clean them out.

1. Press Windows Key + X and select Device Manager.
2. Expand Network adapters. Look for any adapter that isn't your physical Wi-Fi or Ethernet card — things like "Hamachi Network Interface", "TAP-Windows Adapter", "OpenVPN Data Channel", or "Cisco AnyConnect Virtual Miniport".
3. Right-click each one and select Uninstall device. When prompted, check the box that says Delete the driver software for this device.
4. Repeat for each non-physical adapter.
5. Restart your computer.

After restart: Windows will reinstall only the drivers it needs. Launch your app. If the error is still there, the last resort is a full Winsock reinstall using DISM.

3c. DISM and SFC Scan (Nuclear Option)

If none of the above worked, the Winsock files themselves might be damaged. Run these commands in order:

1. Open Command Prompt as Administrator.
2. Run DISM /Online /Cleanup-Image /RestoreHealth — this checks the Windows image for corruption.
3. Wait for it to finish (can take 10-15 minutes).
4. Then run sfc /scannow — this scans and fixes system files.
5. Restart.

What you should see after this: If the error persists after all this, it's likely a hardware issue — bad network card or a motherboard problem. But that's rare. 99% of the time, Step 2 alone fixes it.

Quick Summary Table

Start with Step 1. If that doesn't work, don't waste time — jump straight to Step 2. It's the most reliable fix for WSAEPROTOTYPE 0X00002739. If you're still stuck after Step 3, it's worth posting your exact app and Windows version in a tech forum — someone else has likely seen it before.