You're running an app—maybe a VPN client, a game, or a custom tool you wrote yourself—and it throws WSAEPROTONOSUPPORT (0X0000273B). The full message reads: "The requested protocol has not been configured into the system, or no implementation for it exists." It's infuriating because the app worked yesterday, and you didn't change anything. Except you did, or Windows did during an update. This usually pops up when an application tries to create a socket using a protocol—like IPv6, ICMP, or a raw protocol—that's either uninstalled, disabled, or corrupted in the Winsock catalog.
What actually triggers this error
I've seen this most often with:
- VPN clients (OpenVPN, WireGuard) trying to open a TUN/TAP adapter with a specific protocol.
- Network monitoring tools (Wireshark, Nmap) using raw sockets or custom protocols.
- Games that depend on UDP or IPv6 for multiplayer.
- Custom C# or Python apps using
Socket.ProtocolType.RaworIPV6.
The trigger is almost always a Windows update that removed or corrupted the protocol entry in the registry, or a third-party app (antivirus, firewall) that unregistered the protocol.
Root cause in plain English
Windows uses a layered system called Winsock to map protocol names (like "IPv6" or "ICMP") to actual drivers. Each protocol has a catalog entry in the registry. If that entry is missing, deleted, or points to a driver that's not installed, you get 0X0000273B. The app asks Windows "Hey, give me a socket using protocol X" and Windows shrugs and says "I don't have that protocol loaded."
How to fix it
Skip the obvious reboot—it almost never helps here. Do these steps in order. Stop after each one and test the app again.
Step 1: Check if the protocol is missing from the Winsock catalog
Open Command Prompt as Administrator. Run this command to list all installed protocols:
netsh winsock show catalogLook for the protocol your app needs. Common ones are IPv6, ICMP, or Raw IP. If you don't see it, that's your problem. If you see it but it's marked "disabled", same fix.
Step 2: Reset Winsock
This restores the default protocol catalog. Run this in the same admin command prompt:
netsh winsock reset catalogThen reboot. Yes, you have to reboot for this one.
After reboot, test the app. If it works, you're done. If not, move on.
Step 3: Reinstall IPv6 (if that's the missing protocol)
If the app needs IPv6, and resetting Winsock didn't bring it back, you might need to reinstall it manually.
- Open Network and Sharing Center → Change adapter settings.
- Right-click your active network adapter → Properties.
- If "Internet Protocol Version 6 (TCP/IPv6)" is unchecked, check it and click OK.
- If it's missing entirely, you'll need to add it via the command line:
netsh interface ipv6 installIf the command says it's already installed but the error persists, disable and re-enable it:
netsh interface ipv6 uninstall
netsh interface ipv6 installReboot again.
Step 4: Check for third-party interference
Antivirus software (especially Norton, McAfee, and Kaspersky) sometimes unregister protocols thinking they're a security risk. Temporarily disable your antivirus and test. If that fixes it, add an exception for your app in the antivirus settings. Also check if any network filter drivers (like from Cisco AnyConnect or VMware) are conflicting—they sometimes mess with the Winsock catalog.
Step 5: Manual registry fix (advanced)
If the catalog looks fine but the error persists, the protocol might be listed in the registry but pointing to a non-existent driver. This is rare but happens after a failed driver update.
Back up your registry first. Then navigate to:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Winsock\Parameters\Protocol_Catalog9\Catalog_EntriesYou'll see numbered entries like 00000001, 00000002, etc. Look for entries with a ProviderPath pointing to a file that no longer exists (like a deleted driver). Delete those entries. Be careful—delete the wrong one and you break networking entirely. When in doubt, skip this and just reset Winsock again.
What if it still fails
If none of this works, the problem might be in the application itself. Check if the app supports the protocol you're requesting. For example, if you're asking for IPv6 on a network that only has IPv4, the app needs to handle fallback gracefully—that's not on Windows. Also, some custom apps hardcode a protocol number that Windows doesn't recognize. Try changing the app's code to use ProtocolType.Unspecified or ProtocolType.Tcp instead. If you can't modify the code, contact the app developer.
Finally, run a system file checker scan to rule out corruption deeper in the OS:
sfc /scannowThen DISM /Online /Cleanup-Image /RestoreHealth. Yes, it's a cliche fix, but I've seen it resolve protocol errors that nothing else would touch.
That's it. You should be back up and running. If not, drop a comment with the exact app and protocol—I've debugged this error on hundreds of machines and might have a specific workaround.