400 5160 Error Code

I've got a number of GET search sheet requests returning the following error code:

REST Connector: The remote server returned an error: (400) Bad Request: { "errorCode" : 5160, "message" : "The characters *, ~, : and \" have special meaning in search. Please ensure that your search contains more than just special characters.", "refId" : "5z3m7xl43cym" }: Exceeded maximum attempts (6)

The search query does not contain any special characters. Can anyone give me any insight into why I might be seeing this error?