"Requested Dialog Model not found: Reassign Incident" occurs when trying to reassign a ticket. Additionally, you may notice that some tickets may have the "Escalated" status.
This particular issue can occur if ServiceDesk 7 MR1 hotfixes have been applied to a ServiceDesk 7 MR2 (or possibly ServiceDesk 7.1) installation. Because there are significant differences in the basic workflows governing incidents, these updated projects reference elements in other projects that are build-specific.
To resolve this, you will need to revert the projects to their previous state. The best way to accomplish this is to follow this article and return them to their out-of-box states:
How to restore a ServiceDesk Workflow project to its out of box version after it has been customized http://www.symantec.com/business/support/index?page=content&id=TECH127262
Please note that if you follow that article, all customizations prior to the hotfixes will be lost and will need to be re-implemented. It is always recommended that any time you do customizations in ServiceDesk that you keep a detailed log to aid re-implementing or troubleshooting errors. Additionally, when applying hotfixes, updates or documented customizations, verify they are designed for the version of the product you are using. Additionally, when applying hotfixes