the problem is resolved, here is the solution:
On CRM with portal primary solution version “portallbase” 8.3 or higher. Go to the entity form attachment section.
Search for the option "attach file save option" and set it to be “Notes”
Issue was fixed. In case you have any CRM without that options and the CRM is affected by the issue please upgrade to 8.3 or higher from Dynamics 365 admin center, solutions, upgrade portal type solution and perform the same change in the field "attach file save option".
