OneNote.ServiceId values changed (+immersiveReader) in Office.js production and beta (undocumented API)
UndocumentedNot in Microsoft's documentation
OneNote.ServiceId, not in Microsoft's documentation, values changed (+immersiveReader) on the Office.js production CDN in 16.0.20619.15190, first seen 26 Oct 2026, 18:50 UTC. Affects OneNote on iOS, Mac and web.
- Production
- values changed (+immersiveReader) in 16.0.20619.15190, first seen 26 Oct 2026, 18:50 UTC; rolling out, on 4% of sampled edges.
- Beta
- values changed (+immersiveReader) in 16.0.20619.15190, first seen 26 Oct 2026, 19:00 UTC; rolling out, on 5% of sampled edges.
What this means for your add-in
Removed or changed values break comparisons and switch statements that use them; added values can show up in data your add-in reads.
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 (OneNote.ServiceId) { … }.
Change history
Changed in the same rollouts
- Word.LineFormat removed
- OfficeCore.FlightingService added
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 OneNote.ServiceId; 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). OneNote.ServiceId is not in Microsoft's documentation.