How to Fix Claude Cowork on Windows: A Complete Troubleshooting Guide (Sept. 2026)

Claude’s Cowork feature launched for Windows on February 10, 2026, promising real-time AI collaboration that can see your screen and interact with applications.

But for many Windows users, the reality has been different like missing Cowork tabs, cryptic “yukonSilver not supported” errors, and API connection failures.

This guide cuts through the confusion with accurate, up-to-date troubleshooting based on real user experiences from the first month of Windows Cowork.

Note: If you are experiencing the specific error “Could not connect to MCP server Claude in Chrome”, See our guide: [Could Not Connect to MCP Server Claude in Chrome: Troubleshooting Guide].

Understanding the Current State of Cowork on Windows

Let’s be honest upfront: Cowork on Windows is still quite rough around the edges. The feature relies on complex virtualization technology, and the initial release has encountered significant growing pains.

Based on hundreds of user reports from February–March 2026, many issues stem from bugs in Claude’s platform detection rather than misconfigured systems.

The good news? Regular Chat mode works perfectly for everyone. The challenges are specific to Cowork’s virtual machine environment.

For developers concerned about secure AI-assisted workflows, our companion guide on Claude Code Security covers enterprise safety measures.

Identifying Your Specific Issue

Before diving into solutions, diagnose exactly what’s going wrong. Cowork problems on Windows fall into five distinct categories:

Take a moment to match your experience, it will point you toward the most relevant solutions.

Prerequisites: What You Actually Need

Based on current user reports, here’s the real situation with system requirements:

Windows Edition: The Critical Factor

• Windows 11 Pro: Best supported, but still experiencing detection bugs
• Windows 11 Home: Unclear support status. Hyper-V is not available on Home edition . Some users report Cowork working initially, then breaking after updates. Anthropic has not officially clarified whether Home is supported.
• Windows 10 Pro: Users report the same “yukonSilver not supported” errors despite Hyper-V being fully enabled. It’s unclear if Windows 10 is officially supported at all.

Required Windows Features

If you’re on a supported edition, you need:

• Hyper-V (Windows Pro/Enterprise only—not available on Home)
• Virtual Machine Platform
• Windows Hypervisor Platform
• Windows Subsystem for Linux (WSL2)

Hardware Requirements

• Processor: Intel VT-x or AMD-V enabled in BIOS
• RAM: 16 GB minimum recommended
• Storage: At least 10 GB free space

Step-by-Step Troubleshooting Guide

Step 1: The 30-Second Quick Check

Verify your subscription plan. Cowork requires a Pro or Max plan. Free and Trial accounts cannot access it—the tab simply won’t appear.

Disable any VPN temporarily. VPNs can interfere with regional licensing checks. Turn it off, restart Claude, and check if the Cowork tab appears.

Step 2: Fix Installation Problems

If you installed Claude before February 10, 2026, you likely have the older Squirrel-based package. You might see a banner saying “Cowork requires a newer installation” with a “Reinstall” button that does absolutely nothing when clicked.

The “Check for Updates” feature falsely reports you have the latest version.

The fix requires a manual upgrade:

• Fully uninstall Claude Desktop via Settings → Apps → Installed apps
• Remove leftover files (see Step 3 below)
• Download the fresh MSIX installer from claude.ai/download
• Install as Administrator (right-click the installer and select “Run as administrator”)

Warning: This process may disrupt local MCP server configurations and desktop extensions. Back up any custom configurations first.

Step 3: Clean Reinstallation (When Nothing Else Works)

If you’re still stuck, a complete cleanup often helps:

Uninstall Claude Desktop normally, then open PowerShell as Administrator and run:

Restart your computer, then download and install the latest version from the website.

Step 4: Enable Virtualization Correctly

If you’re seeing “Virtualization is not available” errors:

First, check BIOS/UEFI:

• Restart your computer and press the key to enter BIOS (F2, Del, F10, or F12)
• Find and enable Intel VT-x (Intel) or SVM Mode (AMD)
• Save and exit

Special case: Gaming anti-cheat software (Valorant, Vanguard, etc.)

If you play games like Valorant that use kernel-level anti-cheat, your BIOS virtualization settings may have been deliberately disabled by the anti-cheat system.

This silently breaks Claude Cowork, WSL, Docker, and VirtualBox. Windows-level fixes won’t help because the setting is disabled at the hardware level.

To fix this:

• Enter BIOS again (Delete or F2 on boot). If your keyboard doesn’t work on boot, go to Settings → System → Recovery → Advanced Startup → Restart Now, then choose Troubleshoot → Advanced Options → UEFI Firmware Settings.
• Switch to Advanced Mode (usually F7)
• Navigate to Advanced → CPU Configuration and enable:
  • Intel VMX Virtualization Technology or Intel VT-x (Intel CPUs)
  • SVM Mode (AMD CPUs)

• Navigate to Advanced → System Agent Configuration and enable:
  • VT-d (Intel Virtualization for Directed I/O)
• Press F10 to save and exit

Note: Re-enabling virtualization may cause some anti-cheat systems to complain or require a game reinstall. You may need to choose between gaming and virtualization-dependent apps like Claude Cowork.

Thanks to reader Frédéric Aubuchon for contributing the gaming anti-cheat BIOS fix, which helped identify a critical gap in the original troubleshooting steps.

Then enable Windows features:

• Press Windows key + R, type optionalfeatures, press Enter
• Enable:
  • ✅ Hyper-V (if available—Pro/Enterprise only)
  • ✅ Virtual Machine Platform
  • ✅ Windows Hypervisor Platform
  • ✅ Windows Subsystem for Linux

• Click OK and restart

Verify virtualization is working:

• Open Task Manager → Performance tab → CPU → “Virtualization: Enabled”
• Or run systeminfo in PowerShell and look for: “A hypervisor has been detected.”

Why this is confusing: Cowork’s error message gives no indication that BIOS is the cause — it just says to restart. If you’ve tried everything at the Windows level and nothing works, BIOS is worth checking, especially if you game.

Step 5: Diagnose the “yukonSilver Not Supported” Error

The yukonSilver not supported error remains the most common Cowork issue on Windows, and it is still an Anthropic-side bug, not your system misconfiguration. As of mid-2026, users on fully capable Windows 11 Pro, Enterprise, and Education editions with all virtualization features verified enabled, continue to see:

[info] [cleanupVMBundleIfUnsupported] yukonSilver not supported (status=unsupported), checking for stale bundle...
[startVM] VM not supported (win32/x64), skipping

This is the same pattern reported in GitHub issues #25136, #32004, #32837, and #38373.

Version 1.6608.2 Broke Previously Working Installations

A critical regression was identified in May 2026:

Version 1.6608.2 can break a previously working Cowork installation mid-session—with no Windows updates, no reboots, and no configuration changes. One user reported the transition from working to broken happened immediately after Claude Desktop auto-updated; the yukonSilver failure appeared seconds later.

Affects More Editions and Hardware

Some users with Intel 4th Gen CPUs report a second layer of exclusion: not just yukonSilver not supported, but also VM not supported (win32/x64), which appeared from February 2026 onward and may indicate a CPU generation cutoff.

What You Can Try (Limited)

Since this is a bug in Claude’s platform detection code, specifically the isHardwareVirtEnabled() check in the cowork-svc.exe binary, there is no guaranteed user-side fix. However, the following may help in some cases:

• Clean reinstall (with full cache deletion) works for some, but not for users hit by the 1.6608.2 regression.
• Check Windows build number: One user reported that the underlying cause was an outdated Windows build—updating from 24H2 (Build 26100) to 25H2 (Build 26200) resolved it.
• Ensure VirtualMachinePlatform and HypervisorPlatform are both enabled not just Hyper-V as these are available even on Windows 11 Home and may satisfy the detection check.

When to Stop Troubleshooting

If you’ve confirmed:

✅ BIOS virtualization enabled✅ VirtualMachinePlatform, HypervisorPlatform, and Hyper-V enabled✅ CoworkVMService running✅ vmcompute and vmms services running✅ bcdedit hypervisorlaunchtype = Auto

If you still see yukonSilver not supported in logs, you’re waiting for Anthropic to fix this on their side. No amount of PowerShell commands or BIOS tweaking will resolve it.

What You Can Do to Help Anthropic Fix It

• Submit logs through the app: Settings → Help → Submit Logs
• Reference GitHub issues: #25136, #32004, #32837, #38373, #47327, #57717
• Specify your Claude Desktop version (especially if you’re on 1.6608.2 or later)
• Note whether Cowork ever worked and which update broke it
• Include your Windows build number (systeminfo | findstr “Build”) and CPU generation

Step 6: Fix API Connection Failures

If the workspace starts but can’t connect to Claude’s API (common on Windows 11 Home) :

Configure Windows Firewall:

• Open Control Panel → Windows Defender Firewall
• Click “Allow an app through firewall”
• Ensure Claude is allowed on both Private and Public networks
• If not listed, click “Allow another app” and browse to add it

Corporate NTLM Proxy Issue

Special Case: Corporate Networks with NTLM Proxies

If you’re on a corporate network and regular chat works but Cowork fails with “The Claude API can’t be reached from Claude’s workspace,” you may be hitting a missing feature in the Windows version.

The root cause: On macOS, Claude Desktop runs a local proxy to route the Cowork VM’s traffic through the host. This MITM proxy infrastructure is completely absent on Windows.

Without it, the VM has no path to the internet when your corporate network requires NTLM-authenticated proxies.

What you can do:

• Test on a non-corporate network (e.g., personal hotspot) to confirm this is the issue.
• Contact your IT department about a proxy bypass for Claude Desktop.
• Upvote GitHub issues [#33946] and [#29367] to signal demand for this feature.

VPN Incompatibility Issue

VPN Conflicts: A Known Hyper-V NAT Incompatibility

If Cowork works perfectly with your VPN disconnected but fails immediately when connected, you’ve hit a fundamental architectural issue.

The root cause: The Hyper-V NAT layer used by the Cowork VM does not respect your host’s routing table or split-tunnel VPN configurations. The VM’s traffic is forced through the VPN tunnel, breaking the connection to Claude’s API. Split-tunnel settings and persistent routes do not fix this.

The only reliable workaround: Disconnect from your VPN while using Cowork. (Be aware of the security implications on untrusted networks.)

If you must keep your VPN connected: Try switching to a different VPN protocol (e.g., OpenVPN instead of WireGuard) or using a VPN that operates at the application level rather than the network level. These are not guaranteed fixes.

Reset WSL2 networking:

In an Administrator PowerShell, run:

wsl --shutdown
netsh winsock reset
netsh int ip reset
ipconfig /flushdns

Restart your computer and try again.

Step 7: Handle Service Permission Issues

If you get “Access is denied” when trying to remove CoworkVMService:

Try these commands as Administrator

sc.exe stop CoworkVMService
sc.exe delete CoworkVMService

If that fails with access denied, you may need to:

Boot into Safe Mode

Run the commands there

Or use a tool like Autoruns to forcibly remove the service

This is a known installer bug, the service sometimes becomes impossible to remove even for administrators.

The Honest Bottom Line

After reviewing dozens of GitHub issues from real users, here’s the truth about Cowork on Windows:

• If you’re on Windows 11 Pro and have enabled all virtualization features but still see errors, you’re likely experiencing a Claude bug, not a configuration problem. The “yukonSilver not supported” error appears to be faulty platform detection within the app itself.

• If you’re on Windows 11 Home, you may be hitting an actual limitation because Hyper-V is simply not available on Home edition. It’s unclear whether Anthropic intends to support Home or requires Pro/Enterprise.

• If you’re on Windows 10, the situation is similarly unclear. Users with fully enabled Hyper-V report the same detection errors, and there’s no official word on whether Windows 10 is supported.

When to Stop Troubleshooting and Wait for an Update

If you’ve done all of the above and still see:

• yukonSilver not supported in logs
• The Cowork tab missing despite clean reinstall
• Errors that started after an auto-update

You’re likely waiting for Anthropic to fix bugs on their end. No amount of BIOS tweaking or PowerShell commands will resolve faulty app-side detection.

How to Help Anthropic Fix These Issues

• Submit logs through the app: Settings → Help → Submit Logs
• Include GitHub issue numbers in your description: #24918, #25136, #32004, etc.
• Specify your Windows edition and build (e.g., “Windows 11 Pro 25H2 Build 26200.7462”)
• Note whether Cowork ever worked and which update broke it

Conclusion

Claude Cowork on Windows launched with tremendous potential but real growing pains. The most common issues like missing tabs, “yukonSilver” errors, and API connection failures which stem from a combination of unclear system requirements, installation upgrade path problems, and app-side detection bugs.