Intermittent failure while selecting spinner item

When I am trying to select spinner item using XPath sometimes it gets selected but sometimes it is not able to select the item.
Throwing following error:
org.openqa.selenium.WebDriverException: An unknown server-side error occurred while processing the command. Original error: Must provide a selector when finding elements (WARNING: The server did not provide any stacktrace information)

What version of Appium? What is the xpath selector you are using?

What does your code look like.

Have you tried adding a wait? If it works sometime and fails other times it typically a sync issue.