Cursor MCP Troubleshooting: Changes Not Applied After Editing Config

Edited your Cursor MCP config but changes aren't taking effect? This Cursor-specific troubleshooting guide helps you fix issues when config updates don't apply. Learn about restart/reload requirements, config file location confusion, and how to verify the active server list.

Why Config Changes Don't Apply

Cursor only reads the MCP configuration file on startup. Simply saving the file isn't enough—you need to restart or reload:

Common Causes

• Cursor not restarted after config changes
• Window reload not performed (reload may be required)
• Editing wrong config file (location confusion)
• Config file not saved properly
• JSON syntax errors preventing config load
• Cursor caching old configuration

Step 1: Verify Config File Location

First, ensure you're editing the correct file:

Correct Config File Path

Cursor MCP Config Location

~/.cursor/mcp.json

Full paths:

• macOS/Linux: /Users/yourusername/.cursor/mcp.json
• Windows: C:\Users\yourusername\.cursor\mcp.json

Common Location Mistakes

Wrong: Workspace Config

Editing .cursor/mcp.json in your project workspace

Fix: Use the home directory config: ~/.cursor/mcp.json

Wrong: Different File Name

Editing mcp_config.json or cursor-mcp.json

Fix: File must be named exactly mcp.json

Wrong: Wrong Directory

Editing file in ~/.config/cursor/ or other location

Fix: Must be in ~/.cursor/ directory (with dot)

How to Verify File Location

Verify you're editing the right file:

1. Open terminal/command prompt
2. Navigate to home directory: cd ~
3. Check if file exists: ls -la .cursor/mcp.json (macOS/Linux) or dir .cursor\mcp.json (Windows)
4. Open this exact file in your editor

Step 2: Restart vs Reload

Cursor requires either a full restart or window reload to pick up config changes:

Option 1: Full Restart (Recommended)

Full Restart Steps

1. Save the mcp.json file
2. Completely quit Cursor (Cmd+Q on macOS, Alt+F4 on Windows, or File → Quit)
3. Wait 2-3 seconds for process to fully terminate
4. Reopen Cursor
5. Wait for Cursor to fully initialize
6. Check if MCP server appears

Option 2: Reload Window

Reload May Not Always Work

Sometimes reloading the window is sufficient, but not always:

1. Save the mcp.json file
2. Open Command Palette: Cmd+Shift+P (macOS) or Ctrl+Shift+P (Windows/Linux)
3. Type "Reload Window" and select it
4. Wait for window to reload
5. If MCP server still doesn't appear, try full restart instead

Not Just Closing the Window

Simply closing the Cursor window may not fully quit the application. Check:

• macOS: Check Dock for Cursor icon (right-click → Quit if still running)
• Windows: Check system tray for Cursor process
• Linux: Check if Cursor process is still running: ps aux | grep cursor

Step 3: Verify Active Server List

After restarting, verify Cursor has loaded your MCP servers:

Check MCP Server Status

Ways to verify MCP servers are loaded:

• Look for MCP server indicator in Cursor UI
• Check Cursor settings for MCP server list
• Try asking "What MCP tools are available?"
• Look for Corcava tools in available tools list

Test Prompt

Verification Prompt

"What MCP servers are configured? List available MCP tools."

If Corcava MCP is working, you should see tools like list_tasks, get_task, create_task, etc.

Step 4: Check for JSON Errors

Invalid JSON will prevent Cursor from loading the config:

Validate JSON Syntax

JSON Errors Prevent Loading

If your config has JSON syntax errors, Cursor will silently fail to load it:

• Trailing commas
• Missing quotes
• Mismatched brackets
• Comments (JSON doesn't support comments)

See Config JSON Errors for detailed fixes.

Validate Your Config

Test JSON validity:

1. Copy your entire mcp.json content
2. Paste into JSONLint or similar validator
3. Fix any reported errors
4. Save the corrected file
5. Restart Cursor

Step 5: Clear Cursor Cache

Sometimes Cursor caches old configuration. Clear the cache to force a fresh load:

Cache Locations

macOS

rm -rf ~/Library/Caches/com.todesktop.230313mzl4w4u92
# Then restart Cursor

Windows

Remove: %APPDATA%\Cursor\Cache
# Then restart Cursor

Linux

rm -rf ~/.cache/cursor
# Then restart Cursor

Cache Clearing Warning

Clearing cache will remove other Cursor settings. Only do this if other steps haven't worked.

Step 6: Verify Config File Was Saved

Ensure your changes were actually saved to disk:

Save Verification

Check file was saved:

1. Close the file in your editor
2. Reopen ~/.cursor/mcp.json
3. Verify your changes are still there
4. Check file modification timestamp (should be recent)

Common Save Issues

File Not Saved

• Symptom: Changes disappear when you reopen the file
• Fix: Ensure you save the file (Cmd+S / Ctrl+S) before closing

Wrong File Saved

• Symptom: Saved a different file or workspace copy
• Fix: Verify you're editing ~/.cursor/mcp.json (home directory, not workspace)

Quick Fix Checklist

Systematic Troubleshooting

1. ✅ Verified config file location: ~/.cursor/mcp.json (home directory)
2. ✅ Validated JSON syntax (no errors in validator)
3. ✅ Saved the file and verified changes persisted
4. ✅ Fully quit Cursor (not just closed window)
5. ✅ Waited a few seconds after quitting
6. ✅ Restarted Cursor completely
7. ✅ Waited for Cursor to fully initialize
8. ✅ Verified MCP server appears in Cursor
9. ✅ Tested with "What MCP tools are available?" prompt

Still Not Working?

If config changes still don't apply after all steps:

• Check Cursor logs for error messages (Help → Toggle Developer Tools → Console)
• Try creating a minimal config with just Corcava to test
• Verify Cursor version is up to date (older versions may have MCP issues)
• See Tools Not Listed for additional troubleshooting
• Check Connection Failed for network issues

Related Troubleshooting

• Config JSON Errors - Fix JSON syntax that prevents config loading
• Tools Not Listed - Fix issues when tools don't appear
• Cursor Setup - Review Cursor MCP setup guide
• Troubleshooting Index - Browse all troubleshooting guides