Errors: Required fields are missing: [MyCustomObject];
Resolution: Check the parent records to see why they didn't get created. Fix the parent record, and this child record's required field value should get populated. If this does not resolve the issue, check to see if the "Allow Re-parenting" property on the referenced object is set to false.
Errors: insufficient access rights on cross-reference id: a036000000DGtHT;
Resolution: Check the referenced record (a036000000DGtHT) under the Error node to see why it didn't get created. Fix this record and this record should get created/updated.
Errors: invalid cross reference id;
Resolution: One of the reference fields on the object cannot find the referenced object record. Check to see if any one of those Id's is under the Error node and see why it didn't get created. Fix this referenced record and this record should get created/updated.
Errors: AccountAccessLevel, OpportunityAccessLevel, CaseAccessLevel (Account, Opportunity, Case Levels, Con Levels (All, Edit, Edit, Edit) are below organization levels (Edit, None, Read, ControlledByParent));
Resolution: This normally occurs on Share objects. This field must be set to an access level that is at least equal to the organization’s default ContactAccessLevel. This field cannot be updated via the API if the ContactAccessLevel field is set to “Controlled by Parent,” because the application cannot update this field for the associated account owner using the API. Try updating the account owner’s ContactAccessLevel via the Salesforce user interface. Check to see if "Controlled by Parent" is enabled, and if so, disable it.
Errors: operation performed with inactive user;
Resolution: Perform a Mass Transfer of Ownership to update the object records from the inactive user to the active user. Another solution is to activate this user in the destination.
Error: Cannot add custom fields to entity: AccountContactRole
Resolution: For the entity (i.e. object) specified, be sure to set "Do Not Use External Id" for the External Id field.