Tabbed forms in UI15 are not working properly and all form sections are shown

Tabbed forms in UI15 are not working and all form sections are shown. This occurs with all forms. The following error appears:

JS error Uncaught ReferenceError: angular is not defined

1. Switch to UI15.
2. Change settings to tabbed forms.
3. Navigate to Incidents > Open.
4. Switch to default view.
5. Open any incident record.
   Note that the UI sections are shown as a long list and not in tabbed sections.

This issue appears to be transitory and was not reproducible with reasonable frequency. The issue is under review. To receive notifications when more information is available, subscribe to this Known Error article by clicking the Subscribe button at the top right of the article. If you are able to upgrade, review the Fixed In field to determine whether any versions have a permanent fix.