If you are trying to view change orders but get an error that states "There was an error loading your data. Please try again." You may not have the setting enabled in your profile to allow you to view or edit change orders.
A user with Admin permissions can enable this setting by clicking the manage users quick link on the home page, and then edit next to the user they want to edit.
Scroll to the Admin settings section and make sure "Can Create and Update Change Orders" is enabled.