Symptoms

Virtual agent designer fails to load with the following error in the console.

GET https://instance.service-now.com/scripts/convo-builder/thirdparty/intl/locales/NUL.jsx?v=07-14-2018_1223&lang=NUL 404 (Not Found) 
12:36:11.950 $conversation-builder.do:18 GET https://instance.service-now.com/scripts/convo-builder/thirdparty/intl/locales/NUL.jsx?v=07-14-2018_1223&lang=NUL 404 (Not Found) 

Release

London

Cause

User's profile language is set to NUL which doesn't exist.

Resolution

1) Open user record for the user in question
2) Change the language from NUL to a specific language.