Issue
When running an integration with a Salesforce destination the error “Unable to create/update fields: XXX__c. Please check the security settings of this field and verify that it is read/write for your profile or permission set.” is returned.
Cause
The field referenced in the error is a data type of “Master-Detail” and the field is configured NOT to allow reparenting.
When the integration runs to update an existing record it will pass the value for the field, and even if the value is the same as the existing value in the relationship this error will occur.
Resolution
Edit the field in Salesforce and check the box for “Representable Master Detail”