Is the file used in a conversion task?
Not sure if the issue is related to some known SPR.
SWPDM - Integration - SolidWorks
Summary:"An attempt was made to access a file that is exclusively opened by another application" dispatch error on check in
Comments:'Dispatch error 'An invalid pointer was supplied to the method' when trying to update card variables using the EPDM add-in and an EPDM managed Toolbox