The following error can occur on clients with more than 500 locations:

Sorry, an error has occurred ! ERROR : please email this info (and if possible, a brief description of what happened before the error) to :
Line 976 in /home/surfmer/sassiecore_a/2templatedirectory/admin/LocationAdmin.php

To resolve the issue:

From the Clients tab select the Survey.

Select Client and Form Settings.

Scroll and select "More than 500" from Client Size (# of Locations).

Select Save Changes.