Excel v2511 breaks async

[Sergey-Vlasov]

I'm experiencing multiple unit test failures today:

Using: Microsoft® Excel® for Microsoft 365 MSO (Version 2511 Build 16.0.19426.20118) 64-bit

Looks like it is caused by Excel update: 2025 December 03 | Version 2511 (Build 19426.20170)

https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date#version-history

Reverting to Excel v2510 November 20 resolves the problem:

"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe" /update user updatetoversion=16.0.19328.20244

[Sergey-Vlasov]

Setting Excel RTDThrottleInterval to 20 ms resolves Sleep failures, but Disposable tests still fail.

[Sergey-Vlasov]

@govert Do you think we should wait for a fix from MS or try to adapt our implementation/tests?

[govert]

Can you explain what goes wrong?
Is it possible to reproduce based on the RtdClock-ExcelRtdServer example? https://github.com/Excel-DNA/Samples/tree/master/RtdClocks/RtdClock-ExcelRtdServer

[Sergey-Vlasov]

The RtdClock-ExcelRtdServer example shows updated data every 2 seconds. But unit tests fail with delays smaller than 1 second.

[Sergey-Vlasov]

The difference that I can identify: in v2510 RtdServer.DisconnectData is invoked by Excel right after other calls, but in v2511 it is invoked by Excel after a delay of 100-400 ms.

[Sergey-Vlasov]

Maybe I just need to adapt our unit tests for such (significant) disconnect delay.

[govert]

Thanks for looking further.
I think adding some longer waits to the tests is fine for now, but I want to think a bit about the consequences of the delay, and how best to report or ask about the change.