I have been getting error message "
Unable to complete operation.
Error executing tool. Export Web Map : Invalid input. Failed to execute (Export Web Map).
"

Same Web Json tested with arcgis online print service and it is working fine.
When i removed our ArcGIS services and it is working fine with our custom print service . I have tried replacing arcgis online map services with our web services and it is working. When I open our Map Service in a new tab and able to see Rest service with no issues. I have recently upgraded to 11.2 enterprise.
The combination of Our Custom Print Service with our ArcGIS Services is not working.