Word COM Automation fails with DISP_E_TYPEMISMATCH after KB5094126

Question

Word COM Automation fails with DISP_E_TYPEMISMATCH after KB5094126

Dáňová Daniela (MHMP, OIC) 20

After installing cumulative update KB5094126, our application's use of the Microsoft Word COM Automation interface (used to generate documents and convert them to PDF) started failing with the error DISP_E_TYPEMISMATCH ("type mismatch") when calling Word Automation methods.

Machines without KB5094126 are unaffected.
We reproduced the issue in a minimal standalone test app using only the Word COM interface, with no custom application logic involved — so it's not specific to our app.
We tried different parameter marshalling approaches (MFC wrapper changes, direct IDispatch::Invoke calls) without success.
The issue is consistently tied to KB5094126.

Has anyone else hit this, and is there a known workaround or fix planned in a future cumulative update?

Environment: Windows 11 Enterprise, version 24H2.

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Answer accepted by question author

Jason Nguyen Tran 24,545 Independent Advisor

Hi Dáňová Daniela (MHMP, OIC),

You’re not the only one encountering it. The error DISP_E_TYPEMISMATCH after installing KB5094126 has been reported by others as well, and it appears to be a regression introduced by that cumulative update. Since you’ve reproduced it with a minimal test app, it’s safe to say this isn’t tied to your application logic but rather to the update itself.

The most reliable workaround at the moment is to uninstall KB5094126 from Settings > Windows Update > Update history > Uninstall updates and then pause updates temporarily to prevent it from reinstalling. Doing so restores Word COM automation functionality.

If uninstalling isn’t practical in your environment, you may want to run automation tasks on machines that haven’t yet applied KB5094126 until the fix is released. Keeping an eye on the official Windows release notes will help you know when the patch becomes available.

Jason.

Dáňová Daniela (MHMP, OIC) 20 Reputation points

2026-06-30T10:26:46.5+00:00

Thanks Jason, we've already considered uninstalling/pausing KB5094126 as a temporary measure, but that's not really viable for us long-term across the fleet.

We were actually told by our application vendor that the official KB article for this issue mentions a workaround that Microsoft can provide to organizations, but it requires registering a request through official Microsoft support with a specific identifier — rather than the general uninstall approach.

Could you point us to the specific KB article you're referencing, or confirm whether such an identifier-based workaround exists? We'd like to follow up through the proper support channel if so.

Thanks again for your help. Daniela
Jason Nguyen Tran 24,545 Reputation points Independent Advisor

2026-06-30T10:38:26.5333333+00:00

I recommend registering a request through your Microsoft Support channel and citing KB5094126 explicitly, along with the DISP_E_TYPEMISMATCH regression in Word COM Automation. The support team will then be able to confirm whether the targeted workaround applies to your environment and provide the steps.
Dáňová Daniela (MHMP, OIC) 20 Reputation points

2026-06-30T13:13:35.87+00:00

Thanks Jason, that confirms what we suspected.

One follow-up: our organization currently doesn't have an active Unified/Premier Support agreement, and we don't have entitlement access in the Engage Center to open a case there. Before we go down the route of a paid pay-per-incident support request, I wanted to ask — is there any way to obtain this specific workaround without an active support contract (e.g., a public KB article documenting it, a hotfix request process, or another official channel that doesn't require an existing support agreement)?

Or is a paid support case genuinely the only route to get the workaround for this specific KB5094126 regression? tx Daniela
Jason Nguyen Tran 24,545 Reputation points Independent Advisor

2026-06-30T15:04:52.87+00:00

Hi Daniela,

At present, the workaround tied to KB5094126 is not published as a public KB article or hotfix that can be downloaded directly. It is only available through Microsoft Support when a case is opened, and the support team provides the workaround package or configuration guidance after validating the environment. In other words, there isn’t a channel outside of an active support agreement or a pay-per-incident case to obtain it.
Dáňová Daniela (MHMP, OIC) 20 Reputation points

2026-07-01T08:45:42.3466667+00:00

thank you very much for your time and answers Jason
Jason Nguyen Tran 24,545 Reputation points Independent Advisor

2026-07-01T08:52:27.1766667+00:00

Hi Dáňová Daniela (MHMP, OIC),

I hope the response provided some helpful insight. If you find this answer useful, please hit “accept answer” so others can benefit from your exeperiences. Thanks

1 additional answer

Your answer

Dáňová Daniela (MHMP, OIC) 20 Reputation points

2026-06-30T10:26:46.5+00:00

Thanks Jason, we've already considered uninstalling/pausing KB5094126 as a temporary measure, but that's not really viable for us long-term across the fleet.

We were actually told by our application vendor that the official KB article for this issue mentions a workaround that Microsoft can provide to organizations, but it requires registering a request through official Microsoft support with a specific identifier — rather than the general uninstall approach.

Could you point us to the specific KB article you're referencing, or confirm whether such an identifier-based workaround exists? We'd like to follow up through the proper support channel if so.

Thanks again for your help. Daniela
Jason Nguyen Tran 24,545 Reputation points Independent Advisor

2026-06-30T10:38:26.5333333+00:00

I recommend registering a request through your Microsoft Support channel and citing KB5094126 explicitly, along with the DISP_E_TYPEMISMATCH regression in Word COM Automation. The support team will then be able to confirm whether the targeted workaround applies to your environment and provide the steps.
Dáňová Daniela (MHMP, OIC) 20 Reputation points

2026-06-30T13:13:35.87+00:00

Thanks Jason, that confirms what we suspected.

One follow-up: our organization currently doesn't have an active Unified/Premier Support agreement, and we don't have entitlement access in the Engage Center to open a case there. Before we go down the route of a paid pay-per-incident support request, I wanted to ask — is there any way to obtain this specific workaround without an active support contract (e.g., a public KB article documenting it, a hotfix request process, or another official channel that doesn't require an existing support agreement)?

Or is a paid support case genuinely the only route to get the workaround for this specific KB5094126 regression? tx Daniela
Jason Nguyen Tran 24,545 Reputation points Independent Advisor

2026-06-30T15:04:52.87+00:00

Hi Daniela,

At present, the workaround tied to KB5094126 is not published as a public KB article or hotfix that can be downloaded directly. It is only available through Microsoft Support when a case is opened, and the support team provides the workaround package or configuration guidance after validating the environment. In other words, there isn’t a channel outside of an active support agreement or a pay-per-incident case to obtain it.
Dáňová Daniela (MHMP, OIC) 20 Reputation points

2026-07-01T08:45:42.3466667+00:00

thank you very much for your time and answers Jason
Jason Nguyen Tran 24,545 Reputation points Independent Advisor

2026-07-01T08:52:27.1766667+00:00

Hi Dáňová Daniela (MHMP, OIC),

I hope the response provided some helpful insight. If you find this answer useful, please hit “accept answer” so others can benefit from your exeperiences. Thanks

Answer 1

Thanks Jason, that confirms what we suspected.

One follow-up: our organization currently doesn't have an active Unified/Premier Support agreement, and we don't have entitlement access in the Engage Center to open a case there. Before we go down the route of a paid pay-per-incident support request, I wanted to ask — is there any way to obtain this specific workaround without an active support contract (e.g., a public KB article documenting it, a hotfix request process, or another official channel that doesn't require an existing support agreement)?

Or is a paid support case genuinely the only route to get the workaround for this specific KB5094126 regression? Tx Daniela