This occurs when the Short name / Client ID category search returns more than one result.
The query will return more than one result when you have entered brackets in the job search name:
An example of a short name that caused this error:
E.g. "My Short Name (123456)" or using "and" or "&" in the short name.
We cannot determine all the reasons this error may occur, because when we knew the causes we can eliminated the errors.
The brackets cause additional search parameters to be sent to the DMS search.
Remove the brackets (or any wildcard characters) form the short name and the client identifier.