On a VSTO add-in, PresentationSave event is not fired anymore when the presentation is saved with "Save as"

Question

On a VSTO add-in, PresentationSave event is not fired anymore when the presentation is saved with "Save as"

Gradlon 20

Hi,

I am developping VSTO add-ins for PowerPoint, Excel and Word for a few years now.

Since a few weeks, I observed that PresentationSave and PresentationBeforeSave events are not fired anymore when the user saves the presentation with "Save as" mechanism.

This is also true when saving a new presentation for the first time.

This was not the case with previous Office versions, the events were fired just as expected.

I just check with latest MS Office version (2609 - build 20430.20146), and what seems to be a bug is still present.

I tried to update Microsoft Office to the beta channel version 2610 - build 20527.20000) and I observed that the bug is not present in this version.

Is this a known bug / regression?

Thanks

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Answer 1

Dear @Gradlon,

Thank you for the detailed investigation.

Based on your testing, the most significant observation is that the issue reproduces in Version 2609 (Build 20430.20146) but not in Beta Channel Version 2610 (Build 20527.20000). That strongly suggests this is not a problem with your VSTO add-in implementation, but rather a change in PowerPoint behavior between builds.

Additionally, Microsoft documentation states that PresentationBeforeSave is triggered as the Save As dialog appears, so the behavior you are seeing does not appear consistent with the documented event behavior.

I am not aware of a publicly documented bug or KB article covering this specific regression. However, the fact that the issue is not reproducible in the newer Beta build may indicate that a fix has already been implemented and is awaiting rollout to production channels.

One practical recommendation would be to continue using the Beta Channel build for validation purposes, since you've already confirmed the differing behavior between the two builds. That comparison is one of the strongest indicators that this may be a PowerPoint regression rather than an issue in your VSTO implementation.

If you have access to Microsoft Support, I would recommend opening a support case and including the two build numbers along with a minimal reproducible sample. Build-to-build comparisons are often very helpful when investigating potential regressions.

As a temporary workaround, you may also want to avoid relying exclusively on PresentationSave or PresentationBeforeSave for Save As scenarios until the behavior is clarified, particularly if the add-in needs to support Current Channel users.

I hope this information helps point you in the right direction.

Warm regards,

If the answer is helpful, please select "Yes, accept answer". If you have any questions or new updates, please feel free to comment below.

Gradlon 20 Reputation points

2026-10-08T12:27:29.5566667+00:00

Thanks for the answer. I am looking forward to see the next 2610 version to check if it is fixed.
Liora 2,330 Reputation points Independent Advisor

2026-10-08T15:22:58.7233333+00:00

Hi Gradlon,

Thank you for the update and for taking the time to share your findings.

I hope the behavior continues to remain corrected in the upcoming 2610 builds and that the fix eventually makes its way into the production channels as well.

If you notice any changes in future releases, especially once a newer 2610 build becomes available, I would be very interested to hear about the results. Your testing across different channels and build numbers has been extremely helpful in narrowing this down to what appears to be a PowerPoint regression rather than a VSTO implementation issue.

Also, if you feel the response helped clarify the current situation, you may wish to consider marking it as the accepted answer. Even if the answer does not provide a direct fix, it can help other developers quickly understand that:

The behavior differs between builds.

The issue does not appear to be caused by the VSTO add-in itself.

A newer Beta build appears to behave differently, suggesting a possible regression or fix in progress.

This can help others avoid spending time troubleshooting their own code when the root cause may be related to a specific Office build.

Thank you again for the feedback and for contributing your findings to the community.

Kind regards.