b) Closest prior art not suitable or misinterpreted 

Where the board finds that the closest prior art used to assess inventive step should be from another field than that from which the department of first instance selected what it considered the closest prior art, the search is incomplete and the board will remit the case for further prosecution (T 97/14).

If the examining division finds the invention obvious based on a misinterpretation of a piece of prior art , there is a possibility that the search into the state of the art was stopped too early and was incomplete, justifying remittal of the case (T 565/17, T 2496/17)).