In case your API calls fail with HTTP status 403

[rinorway]

Small tip : In case you get these type of errors :

Error : 403 Forbidden

ERROR: (403) Assignment failure: assigned user or team not allowed.;
POST /Myentity; line: 376, file: /var/www/crm/application/Espo/Core/Record/Service.php [] []

Then check the "assignment permission" in the role settings of the role that you assigned to the API user that you used.

I had to set it explicit to "all"