If you are about to perform an Upgrade this may just save the day for you.

A little known about feature introduced in London was Debug Upgrade.

You can read the official documentation here:

https://docs.servicenow.com/bundle/newyork-platform-administration/page/administer/platform-upgrades...

What does it do?

It enables you to quickly identify what objects were skipped, customized, modified during last upgrade etc of a form. Really, really useful when you are faced with a broken form, or functionality!

How to start?

Basically you enable it under System Diagnostics > Session Debug > then click Debug Upgrade

How to use it?

Perform a transaction i.e. open a form and scroll to the bottom of the form. Here you will see the following options:

Click these to expand and review why your form may not be working: