STATUS_PROTOCOL_NOT_SUPPORTED (0XC000A013) – Quick Fix for Windows Pros

Quick answer: Open Windows Features, turn on SMB 1.0/CIFS File Sharing Support (or WebDAV if that's your scenario), reboot. If that doesn't work, check the registry key HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation and verify Start is set to 2.

I've seen this one pop up more times than I'd like, usually in two flavors. The first is a small office trying to access an old network share on a Synology NAS or a legacy Windows Server 2008 machine that still relies on SMB 1.0. The second is when someone's trying to mount a WebDAV drive and the Windows WebClient service isn't running. Both produce that same 0XC000A013 error, and both are stupidly easy to fix once you know what's missing.

What Actually Triggers Error 0XC000A013?

Your computer tried to use a network protocol that isn't installed. Windows 10 and 11 ship without SMB 1.0 enabled by default for security reasons. Microsoft turned it off after the WannaCry mess. But plenty of older network devices—like that 2012 HP printer or a QNAP NAS—still need it. The protocol itself isn't malicious, just ancient and insecure. If you're on a segmented network with no internet-facing exposure, enabling it is fine.

Fix Steps – The Real Fix

1. Open Windows Features. Hit Windows Key + R, type optionalfeatures, press Enter.
2. Find SMB 1.0/CIFS. Scroll down. Expand SMB 1.0/CIFS File Sharing Support. Check the box that says SMB 1.0/CIFS Client. Don't check Server unless you're sharing folders to old devices. Client is usually enough.
3. If you're dealing with WebDAV: Expand Internet Information Services > Web Management Tools > IIS 6 Management Compatibility and check IIS Metabase and IIS 6 configuration compatibility. Then open Services.msc, find WebClient, set it to Automatic and start it.
4. Reboot. This isn't optional. Windows has to rebuild the protocol stack. Skipping the reboot is like changing a tire while driving—pointless.
5. Test your connection. Map the network drive again or run net view \\target-device from an admin command prompt. It should work now.

Alternative Fixes – When the Main Fix Fails

If you enabled SMB 1.0 and rebooted but still get 0XC000A013, something else is blocking the protocol. Had a client last month whose entire print queue died because of this. Turned out group policy had disabled the Workstation service. Check these:

• Check the Workstation service. Run services.msc, find Workstation (LanmanWorkstation). It should be Running and Automatic. If it's disabled, set it to Automatic, start it, reboot.
• Registry check. Open regedit, go to HKLM\SYSTEM\CurrentControlSet\Services\LanmanWorkstation. Double-click Start. The value must be 2 (automatic start). If it's 4 (disabled), change it to 2, reboot.
• Firewall rules. If you're on a domain and group policy blocks SMB ports (445, 139) or WebDAV (80, 443), you'll need to contact your admin. On a workgroup, check Windows Defender Firewall: inbound rules for File and Printer Sharing should be enabled.
• Third-party antivirus. Some security suites (looking at you, McAfee) block SMB 1.0 even after you enable it. Temporarily disable the AV to test. If the error goes away, whitelist the protocol in the AV settings.

Prevention – Don't Let This Happen Again

• Update your old hardware. If your NAS or printer can't do SMB 2.0 or 3.0, replace it. They're a security hole. But if you're stuck with it, at least isolate it on a separate VLAN with no internet access.
• Document your dependencies. Write down which devices need SMB 1.0. When you upgrade Windows, you'll know exactly which optional features to re-enable.
• Use PowerShell to check. Run Get-WindowsOptionalFeature -Online -FeatureName SMB1Protocol to see the current state. Handy for scripting across multiple machines.

Had a client last month whose entire print queue died because of this—turns out a Windows update had silently turned off SMB 1.0. Took me 10 minutes to fix, but they'd been down for two days. Don't be that person. Check your features.