Fixing "self signed certificate in certificate chain" in GitHub Copilot

GitHub Copilot is an AI-powered coding assistant that enhances developer productivity, but many users encounter the "self signed certificate in certificate chain" error when trying to connect to the Copilot service. This comprehensive guide explains the root causes and provides tested solutions.

Understanding the Problem

The "self signed certificate in certificate chain" error occurs when GitHub Copilot cannot establish a secure connection to its servers. This typically happens in corporate environments where network security measures intercept and inspect encrypted traffic.

Why This Happens

Corporate networks often use "man-in-the-middle" security appliances that:

• Intercept SSL/TLS traffic for inspection
• Replace the original site certificates with company-signed certificates
• Create a certificate chain that includes self-signed corporate certificates

Since Copilot's Node.js-based agent doesn't automatically trust the corporate CA certificates installed on your machine, it rejects the modified certificate chain, resulting in the connection error.

Solutions by Environment

Windows Solutions

Method 1: Use win-ca Extension (Recommended)

The most reliable solution for Windows users is installing the win-ca extension:

1. Install the win-ca extension from VS Code Marketplace
2. Open VS Code command palette (Ctrl+Shift+P)
3. Search for "Win-Ca: Inject" and select it
4. Change the injection mode to append (crucial step)
5. Restart VS Code

Method 2: Git Configuration (Temporary Fix)

For a quick temporary workaround:

git config --global http.sslVerify false

Security Note

This disables SSL verification for Git operations, which reduces security. Use only as a temporary solution.

macOS Solutions

Method 1: Use mac-ca Extension

macOS users can install a similar certificate utility:

1. Install the mac-ca-vscode extension
2. Restart VS Code

Method 2: Environment Variable Approach

Add your corporate certificates to Node.js trust store:

# Export your corporate certificate to PEM format if needed
# Then add to Node.js trusted CAs
export NODE_EXTRA_CA_CERTS="/path/to/your/corporate/cert.pem"

Method 3: Keychain Configuration (For Eclipse/SpringTools)

If using Spring Tool Suite or Eclipse-based IDEs:

1. Edit the application configuration file:

   # Open /Applications/SpringToolSuite4.app/Contents/Eclipse/SpringToolSuite4.ini

2. Add this line:

   -Djavax.net.ssl.trustStoreType=KeychainStore

3. Restart your IDE

Manual Script Approach

For advanced users, this script modifies Copilot's extension to bypass certificate validation:

monkey-patch-copilot.sh

_VSCODEDIR="$HOME/.vscode/extensions"
_COPILOTDIR=$(ls "${_VSCODEDIR}" | grep -E "github.copilot-[1-9].*" | sort -V | tail -n1)
_EXTENSIONFILEPATH="${_VSCODEDIR}/${_COPILOTDIR}/dist/extension.js"

if [[ -f "$_EXTENSIONFILEPATH" ]]; then
    echo "Found Copilot Extension, applying 'rejectUnauthorized' patches..."
    perl -pi -e 's/,rejectUnauthorized:[a-z]}(?!})/,rejectUnauthorized:false}/g' ${_EXTENSIONFILEPATH}
    sed -i.bak 's/d={...l,/d={...l,rejectUnauthorized:false,/g' ${_EXTENSIONFILEPATH}
else
    echo "Couldn't find the extension.js file for Copilot..."
fi

Make script executable

chmod +x monkey-patch-copilot.sh
./monkey-patch-copilot.sh

Security Warning

This script disables certificate validation entirely, making your connection vulnerable to interception. Use only as a last resort in trusted corporate environments.

IntelliJ IDEA Solutions

For JetBrains IDE users:

1. Open Settings (Ctrl+Alt+S)
2. Search for "cert"
3. Enable "Accept non-trusted certificates automatically"
4. Restart IntelliJ

Network-Specific Solutions

ZScaler and Other Corporate Proxies

If your company uses ZScaler or similar security software:

1. Temporarily exit the application (if permitted by company policy)
2. Reload the Copilot extension
3. Reconnect to verify functionality

VPN Considerations

Some users reported the issue is VPN-related. Try these steps:

1. Disconnect from corporate VPN
2. Test Copilot connectivity
3. If it works, your VPN may need configuration adjustments

Permanent Enterprise Solutions

For system administrators seeking to permanently resolve this issue:

1. Export your corporate CA certificate from the company certificate store
2. Distribute the certificate to developer machines
3. Configure Node.js to trust the corporate CA:

   # Add to system environment variables or user profile
   export NODE_EXTRA_CA_CERTS="/path/to/corporate/ca-bundle.pem"

4. Update IDE configurations to use the corporate trust store

Troubleshooting Steps

If the above solutions don't work:

1. Check your internet connection and corporate firewall rules
2. Verify your corporate CA certificates are properly installed
3. Test with different networks (hotspot, home network) to isolate the issue
4. Check GitHub status page for service outages
5. Update VS Code and Copilot to the latest versions

Conclusion

The "self signed certificate in certificate chain" error in GitHub Copilot is typically a corporate network configuration issue rather than a problem with Copilot itself. The most effective solution is to ensure your development environment trusts your organization's certificate authority through extensions like win-ca (Windows) or mac-ca (macOS).

For persistent issues, consult your IT department about proper certificate distribution or potential SSL inspection whitelisting for Copilot services.