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Read the guideCursor AI failures split into four categories: (1) Cursor's own backend is down, (2) the underlying AI provider (Anthropic for Claude, OpenAI for GPT-4o) is having issues, (3) your API key or auth token expired, or (4) a local Cursor process is stuck. Tab autocomplete, Chat, and Composer can fail independently, identify which feature is broken before troubleshooting. Verified April 2026.
Tab autocomplete stops suggesting code completely
Cursor Chat panel shows 'Failed to fetch' or spins indefinitely
Composer returns 'Request failed' or 'Model is currently unavailable'
Inline edit (Ctrl+K / Cmd+K) does nothing or shows an error
Cursor shows 'Having trouble connecting to the AI backend' banner
AI features work sometimes but fail randomly mid-session
Cursor routes requests through its own backend to Anthropic (Claude models) and OpenAI (GPT-4o). An outage at any layer breaks AI features. Check Cursor's status page and the underlying model provider status before troubleshooting locally.
Cursor stores auth tokens locally. After several days or after password changes, tokens expire silently, Cursor shows no obvious 'logged out' state but AI features stop working. Re-signing in refreshes the token.
Users who supply their own OpenAI or Anthropic API keys in Cursor Settings see failures when the key is expired, revoked, or over-quota. BYOK failures produce different errors than Cursor-subscription failures.
Cursor releases updates frequently. Versions more than 2-3 weeks old can hit deprecated API endpoints, causing silent failures in specific features (often Composer before Chat). Keeping Cursor updated prevents this.
Corporate firewalls or VPN configurations sometimes block requests to api.cursor.sh, api.anthropic.com, or api.openai.com. This causes total AI failure on some networks but works fine on personal connections.
Cursor's AI service runs as a background process. Occasionally this process crashes without closing the editor, producing an editor that looks normal but silently drops every AI request. A full quit-and-relaunch fixes this.
When to try: First, before anything else
Visit the Cursor Discord server (#status or #outages channel) for real-time reports, this is faster than any official status page. Also check status.openai.com and anthropic.com/status if Cursor uses your chosen model. If there's an active incident, wait it out before troubleshooting locally.
When to try: Before any settings changes
Don't just close the window, fully quit the application. On Mac: Cmd+Q or right-click dock icon → Quit. On Windows: right-click taskbar icon → Close all windows, then check Task Manager for lingering cursor.exe processes and end them. Relaunch after a full quit. This fixes stuck AI service processes.
When to try: If AI worked before but stopped without obvious cause
Open Cursor Settings (Ctrl+Shift+J / Cmd+Shift+J) → Account → Sign Out. Close and reopen Cursor, then sign in again. This refreshes the authentication token. If you use BYOK, re-enter your API key in Settings → Models after signing back in.
When to try: To isolate model-specific vs. Cursor-wide failures
In Cursor Settings → Models, switch from your current model to a different one (e.g., from claude-3-5-sonnet to gpt-4o, or vice versa). If one model works and the other doesn't, the issue is with that specific model provider, not Cursor itself. Continue using the working model until the other recovers.
When to try: If you haven't updated in 2+ weeks
Open the Cursor command palette (Ctrl+Shift+P / Cmd+Shift+P) and run 'Cursor: Check for Updates'. Alternatively, download the latest installer from cursor.com. Run the installer over the existing installation, your settings and extensions are preserved. Restart after updating.
When to try: If you supply your own API key in Cursor Settings
If you're using your own API key: open Cursor Settings → Models → confirm the API key is entered correctly. Go to platform.openai.com/usage or console.anthropic.com to verify the key is active and has remaining quota. Rotate the key if in doubt, generate a new key, paste it into Cursor, test. Do not confuse Cursor subscription credits with BYOK quota; they're separate.
When to try: If you use a VPN or corporate network
Disable VPN and try Cursor AI features on your regular home or mobile hotspot connection. If AI works without VPN but not with it, your VPN is blocking requests to api.cursor.sh or the model provider APIs. As a workaround, temporarily disable VPN for AI features, or add those domains to your VPN's split-tunnel exclusion list.
When to try: If nothing else works
On Mac: quit Cursor, open Finder, press Cmd+Shift+G, navigate to ~/Library/Application Support/Cursor, and delete the Cache and Code Cache folders (your settings in the User folder are safe). On Windows: quit Cursor, open %APPDATA%\Cursor and delete Cache and CachedData folders. Relaunch Cursor. This resolves corrupted cache causing silent AI failures.
Enable auto-updates in Cursor, running outdated versions is the most preventable cause of AI failures
Bookmark the Cursor Discord #status channel for the fastest outage reports
If using BYOK, set up billing alerts on your API key to catch quota exhaustion before it breaks your workflow
Keep a backup model configured (e.g., if using Claude as primary, have GPT-4o as fallback) so you can switch in seconds
On corporate networks, confirm with IT that api.cursor.sh, api.anthropic.com, and api.openai.com are allowlisted
Contact Cursor support at cursor.com/support if: (1) Re-signing in doesn't restore AI features and your subscription shows as active, (2) AI features fail on all models simultaneously with no status incident reported, (3) Cursor charges show on your account but the AI features are locked. For BYOK issues, contact OpenAI or Anthropic support directly, Cursor support cannot help with third-party API key problems.
The most common cause is a stuck AI service process, quit Cursor fully (Cmd+Q on Mac, or End Task in Windows Task Manager) and relaunch. If that doesn't work, sign out and back in to refresh the auth token. Tab completion is usually the first feature to break when auth expires, often before Chat shows any visible error.
Check the Cursor Discord (#status channel) first, it's updated faster than any official page. Also check status.openai.com and anthropic.com/status since Cursor routes through those providers. If all three show operational, the issue is likely local to your machine.
Cursor supports both. By default, Cursor subscriptions include access to Claude 4 Sonnet (Anthropic), GPT-4o (OpenAI), and several other models. You can also bring your own API key for either provider. Each model has separate availability, switching models is the fastest way to keep working when one provider is down.
Composer (multi-file editing) and Chat use different internal pipelines. Composer failures with a working Chat usually point to: (1) the Composer feature hitting a separate rate limit, (2) a Cursor version issue where Composer endpoints were updated, or (3) a file context loading problem. Try updating Cursor first; Composer gets the most frequent fixes in updates.
This error means the AI model Cursor is trying to use is either overloaded or experiencing an outage. It's a model-provider-level error, not a Cursor bug. Switch to a different model in Cursor Settings → Models immediately, if Claude is unavailable, GPT-4o often is, and vice versa. The error usually resolves within 15-30 minutes.
No. All Cursor AI features require an internet connection to reach the AI providers' servers. There is no local model support in Cursor as of April 2026. If you need offline AI coding assistance, VS Code with Ollama (local model runner) is the current best alternative.
No. Signing out only clears the authentication token, your settings, keybindings, extensions, and workspace configurations are stored locally and remain intact. After signing back in, all settings are exactly as you left them. Sign out/in is safe to do as a troubleshooting step.
Your corporate firewall or proxy is blocking Cursor's AI endpoints. The domains to allowlist are: api.cursor.sh (Cursor backend), api.anthropic.com (Claude models), and api.openai.com (OpenAI models). Ask your IT team to add these to the firewall allowlist. Alternatively, configure Cursor to use a proxy that can reach these domains, Cursor inherits the system proxy by default.