Symptoms

• Both Customers and Service Management agents are unable to view/download attachments when opening the issue via SD Portal.
• Agents are able to view attachments when using the Jira interface.

The following is seen on atlassian-jira.log:

failed to check if user can view attachment with reason: The request type you are trying to view does not exist.

Cause 

The issue doesn't have a valid request type. The request type was deleted or the issue was moved from another SD project in which the Issue/Request type association doesn't match the current SD project.

Resolution

Set a valid request type for the issue. This could possibly require an issue-type change as well.