When Your AI Coding Assistant Suddenly Stops Working
You're in the middle of a productive coding session, and suddenly your AI completions disappear. Maybe you see a cryptic "Sign in required" message, or your inline suggestions just stop appearing altogether. Whether you're using VS Code with GitHub Copilot or Cursor with its built-in AI, these disruptions can bring your workflow to a grinding halt.
This guide systematically walks you through diagnosing and fixing the most common AI extension failures in VS Code and Cursor. The solutions here apply to all major AI coding extensions — GitHub Copilot, Codeium, Continue, Tabnine, and Amazon CodeWhisperer.
Common Symptoms and Their Root Causes
When AI extensions malfunction, the symptoms generally fall into four categories.
Authentication and license errors include repeated "Sign in required" prompts, expired token messages, and SSO authentication failures for organization accounts.
Connection and network errors manifest as "Failed to connect to server" or "Request timed out" messages, inability to reach APIs behind proxies, and firewall blocks.
Extension malfunction shows up as disappearing inline completions, unresponsive chat features, and extensions that crash and restart in a loop.
Environment and configuration conflicts occur when multiple AI extensions interfere with each other, after VS Code updates break compatibility, or when settings files become corrupted.
Fixing Authentication Errors
Authentication issues are the most frequently reported problems. Work through these steps in order.
Step 1: Refresh Your Authentication Token
Start by resetting the authentication state from VS Code's Command Palette.
# Open Command Palette
# Ctrl+Shift+P (Windows/Linux) / Cmd+Shift+P (Mac)
# For GitHub Copilot
> GitHub Copilot: Sign Out
> GitHub Copilot: Sign In
# For Codeium
> Codeium: Sign Out
> Codeium: Provide Authentication Token
# Manually clear auth cache (Mac)
rm -rf ~/Library/Application\ Support/Code/User/globalStorage/github.copilot*
# Windows: delete %APPDATA%\Code\User\globalStorage\github.copilot*
# Linux
rm -rf ~/.config/Code/User/globalStorage/github.copilot*Step 2: Verify Organization SSO Authentication
If you're using GitHub Copilot through an organization license, your SSO token may need to be re-authorized.
# Check your current auth status with GitHub CLI
gh auth status
# Expected output:
# github.com
# ✓ Logged in to github.com as username
# ✓ Token: ghp_****
# ✗ Token is not authorized for SSO organization: your-org
# Re-authorize with Copilot scope
gh auth refresh -h github.com --scopes "copilot"This opens a browser window for SSO authentication. Make sure your organization admin has assigned you a Copilot seat as well.
Step 3: Verify Your License Status
# Check Copilot subscription via API
curl -H "Authorization: Bearer $(gh auth token)" \
https://api.github.com/copilot_internal/v2/token 2>/dev/null | \
python3 -c "import sys,json; d=json.load(sys.stdin); print(f'Expires: {d.get(\"expires_at\",\"N/A\")}')"
# Expected output:
# Expires: 2026-04-10T20:00:00+00:00
# → If the date is in the past, your subscription needs renewalFixing Connection Errors
Step 1: Diagnose Network Connectivity
Verify that your machine can reach the AI extension's backend API endpoints.
# Check GitHub Copilot endpoint
curl -sI https://copilot-proxy.githubusercontent.com/v1/engines | head -5
# Expected: HTTP/2 401 (reachable even without auth)
# Check Codeium endpoint
curl -sI https://server.codeium.com | head -5
# Check current proxy settings
echo "HTTP_PROXY: ${HTTP_PROXY:-not set}"
echo "HTTPS_PROXY: ${HTTPS_PROXY:-not set}"
echo "NO_PROXY: ${NO_PROXY:-not set}"Step 2: Configure VS Code Proxy Settings
In corporate networks or VPN environments, VS Code needs explicit proxy configuration for AI extensions to communicate with their backends.
// Add to settings.json
{
"http.proxy": "http://proxy.example.com:8080",
"http.proxyStrictSSL": false,
"http.proxyAuthorization": null,
"github.copilot.advanced": {
"debug.overrideProxyUrl": "http://proxy.example.com:8080"
}
}Step 3: Configure Firewall Allowlists
The following domains must be accessible for each AI extension to function.
copilot-proxy.githubusercontent.com(GitHub Copilot)api.github.com(GitHub authentication)server.codeium.com(Codeium)api.tabnine.com(Tabnine)*.amazonaws.com(CodeWhisperer)
# Connectivity check script for all endpoints
for host in copilot-proxy.githubusercontent.com api.github.com server.codeium.com api.tabnine.com; do
if curl -sI --connect-timeout 5 "https://$host" > /dev/null 2>&1; then
echo "✅ $host — Connected"
else
echo "❌ $host — Failed (check firewall or DNS)"
fi
done
# Expected output:
# ✅ copilot-proxy.githubusercontent.com — Connected
# ✅ api.github.com — Connected
# ✅ server.codeium.com — Connected
# ✅ api.tabnine.com — ConnectedFixing Extension Malfunction
Step 1: Clean Reinstall
When extension internals become corrupted, a clean reinstall is the most reliable fix.
# Uninstall via VS Code CLI
code --uninstall-extension github.copilot
code --uninstall-extension github.copilot-chat
# Remove cached extension files (Mac)
rm -rf ~/.vscode/extensions/github.copilot-*
rm -rf ~/Library/Application\ Support/Code/CachedExtensionVSIXs/github.copilot*
# Reinstall
code --install-extension github.copilot
code --install-extension github.copilot-chat
# Fully restart VS Code (not just close/reopen the window)
# Mac: Cmd+Q → reopen
# Windows: End all Code processes in Task Manager → reopenStep 2: Check Output Logs
The extension's detailed error logs are your best tool for pinpointing the exact failure.
VS Code menu:
View → Output → Select the extension name from the dropdown
Channels to check:
- "GitHub Copilot" — API communication logs
- "GitHub Copilot Chat" — Chat feature logs
- "Extension Host" — Overall extension startup logsLook for keywords like ECONNREFUSED (connection blocked), ETIMEOUT (timeout), and 401 Unauthorized (authentication failure) to narrow down the issue.
Step 3: Cursor-Specific Fixes
Cursor uses its own AI backend, so some troubleshooting steps differ from VS Code.
# Reset Cursor settings (Mac)
rm -rf ~/Library/Application\ Support/Cursor/User/globalStorage/cursor*
rm -rf ~/Library/Application\ Support/Cursor/Cache
# Reset Cursor settings (Windows)
# Delete %APPDATA%\Cursor\User\globalStorage\cursor*
# Delete %APPDATA%\Cursor\Cache
# Reset Cursor settings (Linux)
rm -rf ~/.config/Cursor/User/globalStorage/cursor*
rm -rf ~/.config/Cursor/CacheIn Cursor, you can also try switching models under "Settings → Models" to bypass API issues with a specific model provider.
Resolving Multiple AI Extension Conflicts
Step 1: Diagnose the Conflict
Running multiple AI completion extensions simultaneously can cause flickering suggestions, extreme latency, or completions that never appear.
// In settings.json, explicitly set completion priorities
{
// Use GitHub Copilot as primary completion provider
"editor.inlineSuggest.enabled": true,
"github.copilot.enable": {
"*": true,
"plaintext": false,
"markdown": false
},
// Disable Tabnine inline completions (keep chat only)
"tabnine.experimentalAutoImports": false,
// Disable Codeium inline completions
"codeium.enableCodeLens": false
}Step 2: Use VS Code Profiles
VS Code's profile feature lets you switch between AI extensions cleanly based on your current task.
# Create a Copilot-focused profile
# Command Palette: > Profiles: Create Profile
# → Name: "AI - Copilot"
# → Enable only GitHub Copilot extensions
# Create a Codeium-focused profile
# → Name: "AI - Codeium"
# → Enable only Codeium extension
# Switch between profiles as needed
# Command Palette: > Profiles: Switch ProfileVerifying the Fix
After applying any of the solutions above, verify that everything is working correctly.
# 1. Check Developer Tools for errors
# Ctrl+Shift+I (Windows/Linux) / Cmd+Opt+I (Mac)
# Look for errors in the Console tab
# 2. Check status bar indicators
# - GitHub Copilot: Copilot icon in bottom-right, not spinning
# - Codeium: "Codeium: Connected" in bottom-right
# 3. Test completions (in any .js file)
# Type: function fibonacci( → inline completion should appear
# 4. Test chat (Copilot Chat / Cursor Chat)
# Ask: "Hello, can you explain what this file does?" → should get a responsePrevention: Best Practices to Avoid Recurring Issues
A few habits can help you avoid most AI extension failures before they happen.
Keep auto-update enabled: Set "extensions.autoUpdate": true so you're always on the latest version. That said, right after a major update, it's wise to wait a day or two before updating in a team environment.
Keep VS Code up to date: AI extensions depend on the latest VS Code APIs. Running an outdated editor version is one of the most common sources of subtle compatibility issues.
Re-authenticate after network changes: Whenever you switch between VPN, office, and home networks, proactively refresh your authentication tokens to avoid unexpected sign-out mid-session.
Clear extension caches monthly: A quick monthly cache purge prevents accumulated stale data from causing mysterious failures down the road.
Looking back
When AI extensions stop working in VS Code or Cursor, the most efficient approach is to classify the symptom into one of four categories — authentication error, connection error, extension malfunction, or extension conflict — and then follow the corresponding fix steps. In most cases, refreshing your authentication token and performing a clean reinstall of the extension will resolve the issue.
For more complex scenarios, reviewing network settings or separating extensions into VS Code profiles provides a stable long-term solution. Building habits like monthly cache clearing and keeping auto-updates on will prevent most of these issues from recurring.
If you're considering migrating to Antigravity, check out our VS Code to Antigravity migration guide and common Antigravity editor issues and fixes for a smooth transition.