Can't attach to session. Error response status 13. Haven't changed my setup

I can no longer attach to sessions. Have been using Appium for weeks. My set up hasn’t changed today. Hooking into an iOS app running on Xcode Simulator.

Any ideas as to where to look? I’ve restarted everything and am running the latest version of Appium (1.1.0-beta.4). I updated from a version that’s about a month old, had the error on both versions.

[sessionCapabilities()] Error response status: 13, , UnknownError - An unknown server-side error occurred while processing the command. Selenium error: Unable to find session with requested ID:2080380e-62c6-4748-9ea7-64ba232ede1d. The session might have been closed if no request came in 90000ms or never existed Build info: version: ‘unknown’, revision: ‘unknown’, time: ‘unknown’ System info: host: ‘ae80cfd6dba2’, ip: ‘’, ‘Linux’, os.arch: ‘amd64’, os.version: ‘4.8.0-45-generic’, java.version: ‘1.8.0_131’ Driver info: driver.version: unknown

I fixed it. In the GUI interface, Appium had defaulted to ‘Automatic Server’. I selected the ‘Custom Server’ tab and it started working again. Not sure why it did that as I’ve been running it for a long time without it defaulting back to ‘Automatic Server’.