During the update, the Sage 50 database misplaces the location of the custom forms
Resolution
Browse to the default Forms folder in C:\Program Files\Sage 50 *** Edition\Forms or C:\Program Files(x86)\Sage 50 *** Edition\Forms or do an extension search for .sfm files in Windows.
Copy the customised forms and paste them in a folder on the local drive eg. C:\Sage or C:\Sage 50 Forms.
Install the new release.
Find out where your custom forms were stored.
Select Setup, Reports and Forms to locate form name.