If you're using OS X Yosemite v10.10.5 and see a message, "An error occurred while configuring your Server" when you open Server app, make sure you've installed the OS X Server v4.1.5 update. To avoid interruption of services, OS X Server updates aren't installed automatically.
Use these steps to update your server:
- Quit Server app.
- From the Apple menu, choose App Store.
- Click the Updates icon in the App Store window.
- Select the option to update your server to OS X Server v4.1.5.
After installation is complete, open Server app to finish the update and setup process.