An user can not create an issue via some specific customer portal views.
When an error occurred, I got the message below in catalina.out.
"http-bio-8080-exec-21 DEBUG XXXXX 1343x17796x1 ul5a1t 10.40.240.167 /rest/analytics/1.0/publish/bulk [analytics.client.listener.ProductEventListener] Sending event message servicedesk.page.view.customerview.createRequest.saveFailed took 1236 µs"
Please let me know if any further information is required.