Scenario: Use the Partner API to update a custom field, on a custom object, installed via a managed package. While the integration flow worked correctly in developer sandboxes - Production flow was throwing an error that had not been seen in testing: [InvalidSObjectFault [ApiQueryFault [ApiFault exceptionCode='INVALID_TYPE' exceptionMessage='CUSTOMFIELD_C FROM MANAGED_PACKAGE_OBJECT__C WHERE EXTIDFIELD__C ERROR at Row:1:Column:41 sObject type 'MANAGED_PACKAGE_OBJECT__C' is not supported. If you are attempting to use a custom object, be sure to append the '__c' after the entity name....