OfficeExtension.ClientRequestContextBase: 2 API changes in Office.js (undocumented API)
UndocumentedNot in Microsoft's documentation
OfficeExtension.ClientRequestContextBase, not in Microsoft's documentation, shape changed (function → class) on the Office.js production CDN in 16.0.20612.15140, first seen 22 Oct 2026, 21:50 UTC. Affects Excel on Mac, Windows, Android and Windows (WinRT), OneNote on web and Windows, Visio on web and Windows, Word on Mac and PowerPoint on iOS.
- Production
- shape changed (function → class) in 16.0.20612.15140, first seen 22 Oct 2026, 21:50 UTC; rolling out, on 5% of sampled edges.
- Beta
- shape changed (function → class) in 16.0.20612.15140, first seen 22 Oct 2026, 22:20 UTC; rolling out, on 2% of sampled edges.
What this means for your add-in
The member changed shape (for example a function became a property or an object); code that calls or reads it the old way breaks.
It is not in Microsoft's documentation (neither @types/office-js nor @types/office-js-preview): an internal API that can change in any build. Do not depend on it; if you must, check that it exists before use — if (OfficeExtension.ClientRequestContextBase) { … }.
Change history
Changed in the same rollouts
- OfficeExtension.ClientRequestBase implementation
- OfficeExtension.OperationalApiHelper shape
- Word.SensitivityLabelUpdateStatus renamed
Source
silentship samples every Office.js file on the CDN every 10 minutes and compares the public API surface of each new build with the previous one by reflection. This page lists what changed for OfficeExtension.ClientRequestContextBase; it does not include Microsoft's code. The API status comes from Microsoft's published type definitions (@types/office-js and @types/office-js-preview). OfficeExtension.ClientRequestContextBase is not in Microsoft's documentation.