Warning: the session transformation <SESSTRANSFORMATIONINST name> does not exist in the mapping <mapping name> in target folder.
In the XML file, you specified SINSTANCENAME and TRANSFORMATIONTYPE attributes in a SESSTRANSFORMATIONINST element that does not match a transformation in the mapping associated with the session. This might have happened if you deleted the transformation in the mapping after you exported the session.
Edit the XML file, and verify the SESSTRANSFORMATIONINST element refers to an existing transformation in the referenced mapping. Or, edit the session after you import it.