A dependent field's choice with value NULL_OVERRIDE (used to replace the default -- None -- option) does not work if the depended on field has a value - Known Error

A dependent field's choice with value NULL_OVERRIDE (used to replace the default -- None -- option) does not work if the depended on field has a value Description You can define a choice on a choice list and enter the value NULL_OVERRIDE to replace the default '-- None --' option, as per the following product documentation: https://docs.servicenow.com/

However, when applied to a dependent choice list, the NULL_OVERRIDE choice only works properly if nothing is selected in the depended on choice field. If a value is selected in the depended on choice field, the '-- None --' option becomes selectable in the list and is not replaced by the NULL_OVERRIDE choice. Steps to Reproduce

Navigate to Incident > Create New . Right-click on the Subcategory label and choose Show Choice List . Click New . For the Table field, choose Incident [incident] . For the Element field, ensure it's set to Subcategory . As the Value , set it to NULL_OVERRIDE . For the Label field, set it to anything that's easy to differentiate from the default -- None -- text, such as -- CHOOSE ONE (TEST) -- . Click Save . Navigate to Incident > Create New . Choose the -- None -- option in the Category field. Note that the option you set in step 7 is available in the Subcategory choice list. Choose any other option in the Category field (for example, Network ). Note that the option you set in step 7 is no longer available for selection in the Subcategory choice list, and instead the -- None -- option is now available for selection:

Expected behavior: The defined NULL_OVERRIDE option should replace the -- None -- option both when something is selected in the depended on choice field, as well as when nothing is selected in the depended on choice field.

Actual behavior: The -- None -- option becomes available again when something is selected in the depended on choice field:

Workaround There is currently no known workaround for this issue. To receive notifications when more information is available, subscribe to this known error article (click Subscribe button at the top of the article).