The following error occured for me several hours ago (I have not changed anything in the setup, it was working fine before). I am using the latest appium version and xcuidriver (downloaded separately). I tried to delete fully appium and xcuidriver and install them again. Nothing helps…
ERROR webdriver: unknown error: An unknown server-side error occurred while processing the command. Original error: Could not find a driver for automationName ‘XCUITest’ and platformName ‘iOS’. Have you installed a driver that supports those capabilities? Run ‘appium driver list --installed’ to see. (Lower-level error: Cannot find module ‘/…./node_modules/appium-xcode/build/lib/index.js’. Please verify that the package.json has a valid “main” entry)