I am having an issue while updating an existing community contact/account:
Contact has 'created by' and 'Owner' set to Salesforce Standard User. And then from that Contact I created a community user.
Now with REST API I am trying to update that Contact's 'owner' field to Community user I see following error:
Portal users cannot own partner accounts
Best Answer
This error message is confusing. Basically, the system will prevent portal users from owning contacts that are linked to any kind of account, according to this knowledge article: https://help.salesforce.com/articleView?id=000004491&language=en_US&type=1
The only way for you to avoid the error is to use a beforeInsert trigger to change the contact ownership to an internal Salesforce license user.