When trying to edit a custom application or to open Studio, the following error message may display and/or appear in the localhost log:

  "_ undefined, maybe missing global qualifier"

When trying to open the application in Studio, it keeps the 'Loading Application' screen without completing.

1. Navigate to System Applications > Applications.

2. Click the edit button on the application.

   The system tries to open the application in Studio, which keeps loading.

3. Clicking on the application name.

   The system tries to open the application form to edit it, and the error message displays in that screen
   
   

This is what is shown in the localhost logs : 
 
WARNING *** WARNING *** Evaluator: java.lang.SecurityException: _ undefined, maybe missing global qualifier 
 
Caused by error in Script Include: '_' at line 6 
 
3: // (c) 2009-2015 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors 
4: // Underscore may be freely distributed under the MIT license. 
5: 
==> 6: (function() { 
7: 
8: // Baseline setup 
9: // -------------- 
2017-07-10 07:12:55 (695) API_INT-thread-1 58ABB5BEDBF332005D69F7671D9619D0 WARNING *** WARNING *** Evaluator: java.lang.SecurityException: _ undefined, maybe missing global qualifier 
Caused by error in sys_ws_operation.cfb3fd7237930200612747efbe41f15e at line 25 
 
22: push = ArrayProto.push, 
23: slice = ArrayProto.slice, 
24: toString = ObjProto.toString, 
==> 25: hasOwnProperty = ObjProto.hasOwnProperty; 
26: 
27: // All **ECMAScript 5** native function implementations that we hope to use 
28: // are declared here. 

error "_ undefined, maybe missing global qualifier" is caused by script include with  name "_".

Any release that has the Application Studio

A custom script include has the name '_' which conflicts with a base system script include with the same name.

1. Search for script includes with the name '_' using the following URL:

   https://<instancename>.service-now.com/sys_script_include_list.do?sysparm_query=GOTOname%3D_

   This should result in two rows, one for application Studio and one for application Code Search.

2. Rename, delete, or deactivate any others.

   Confirm that this resolves the issue.