If your AI client isn’t connecting to the Sketch MCP Server or certain tools aren’t behaving as expected, don’t worry — most issues are quick to resolve.
Can’t start the server
If you can’t start the server make sure Sketch is enabled in System Settings > Privacy & Security > Local Network. If Sketch is already enabled, toggle the switch off and back on again. Relaunch Sketch and try again. If the issue persists, please let us know.
How to change the local port number
If you’re experiencing errors starting the MCP server, you may need to change the local port number it uses. To do this, quit Sketch and then run the following Terminal command:
defaults write com.bohemiancoding.sketch3 mcpServerPortNumber -int 1234
…where 1234 is any number in the 1024…49151 range. Relaunch Sketch and try to start the MCP server as usual.
To return back to the default port value, run the following Terminal command and restart Sketch:
defaults delete com.bohemiancoding.sketch3 mcpServerPortNumber
Restore default port
To restore the default port, run this command and restart Sketch:
defaults delete com.bohemiancoding.sketch3 mcpServerPortNumber
Make sure the port you choose isn’t already in use by another local service. If Sketch still can’t start the MCP Server after changing ports, try a different number within the recommended range or restart your computer before relaunching Sketch.
