canon – How to combine an autofocus teleconverter with a manual-focus lens


I have a teleconverter (Bower MC 2x C/AFI) which has pins to connect the lens electronics to the camera body. It works well with my autofocus lenses. If I try to use the converter with a manual-focus lens for example the Samyang 135mm F2.0 I always get the following error:

Err 01
Communication between the camera and lens is faulty. Clean the lens contacts.

Camera body is a Canon 90D or 550D (same behavior on both). The lens contacts are clean. The picture is actually taken successfully but the error prevents me from taking more pictures.

Question(s)

  1. Is there any way to avoid this error?
  2. Are there any teleconverters specifically for manual-focus lenses? I cannot seem to find any online.