Word hangs when modifying a style on Windows Server 2019

Kaas 0 Reputation points
2026-09-15T05:29:20.56+00:00

Hello,

we are experiencing a reproducible issue with Microsoft Word for Microsoft 365 Apps. When an affected user tries to modify a Word style using the Modify Style dialog, Word becomes completely unresponsive and does not recover. The WINWORD.EXE process must then be terminated manually.

At approximately the same time, the following error appears in the Windows Application event log:

  • Source: .NET Runtime
  • Event ID: 1022
  • .NET Runtime version: 4.0.30319.0
  • HRESULT: 0x80004005
  • Message ID: [0x2509]

Translated event message:

There was a failure initializing the profiling API attach infrastructure. This process will not allow a profiler to attach. HRESULT: 0x80004005. Process ID (decimal): 19144. Message ID: [0x2509].

The issue previously also occurred on our Windows 11 devices. Since installing the September 2026 .NET update KB5126052, we can no longer reproduce the problem on Windows 11.

However, the issue remains reproducible on our Windows Server 2019 Remote Desktop Session Hosts. Installing the corresponding .NET update KB5126048 did not resolve it.

We understand that Event ID 1022 does not by itself prove that the .NET error causes the Word hang. However, the different behavior after the Windows 11 .NET update suggests that a .NET component, managed Word add-in, security component, or profiler may be involved.

Microsoft 365 Support advised us that this was not considered a Word issue and recommended posting it in the Community forum.

Has anyone experienced the same behavior on Windows Server 2019? Is there an additional fix for Server 2019 corresponding to the reliability improvement included in KB5126052, or are there specific Word add-ins, .NET profilers, or security components known to cause this issue?

Thank you.

Microsoft 365 and Office | Word | For business | Windows
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  1. Charles Kenyon 170.9K Reputation points Volunteer Moderator
    2026-09-16T21:10:50.64+00:00

    Not providing an answer... just some thoughts...

    There are a number of ways to modify a style including the Modify Style dialog and applying directt formatting to text in the style and then telling Word to update the style to match formatting.

    Is this happening no matter how the style is being modified?

    All documents or only those based on particular templates?

    Does it happen if Word is started in safe mode?

    https://support.office.com/article/dedf944a-5f4b-4afb-a453-528af4f7ac72

    This is a user-to-user support forum. Microsoft will not know about the problem from your post here. You would need to use the feedback mechanisms and perhaps open a support ticket for them to see it.

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  2. Hani-Ng 1,575 Reputation points Independent Advisor
    2026-09-15T05:54:44.99+00:00

    Hi Kaas

    The .NET Runtime Event ID 1022 does not establish a direct relationship between the .NET runtime event and the Word hang. However, the issue no longer reproducing on Windows 11 after installation of KB5126052, while remaining reproducible on Windows Server 2019 with KB5126048, points to a difference in platform behavior that may warrant further investigation.

    The documentation for KB5126052 includes a .NET reliability improvement for certain 64-bit scenarios, whereas KB5126048 does not list a corresponding reliability improvement.

    At this time, based on my research, there is no published Microsoft documentation describing a specific fix for Word becoming unresponsive when modifying styles on Windows Server 2019, and there is no documentation indicating that the reliability improvement included in KB5126052 is available for KB5126048.

    For troubleshooting purposes, it may be useful to review:

    • Office COM/VSTO add-ins
    • Endpoint security or DLP software
    • Application monitoring or profiling tools
    • .NET profiler-related settings (COR_* or CORECLR_* variables)

    Testing Word in Safe Mode (winword.exe /safe) and temporarily disabling non-Microsoft add-ins may also help determine whether an external component is involved.

    If the behavior continues, collecting a hang dump of WINWORD.EXE while Word is unresponsive may provide additional information about the module or component involved in the hang.

    Based on the currently available documentation, there does not appear to be a separately documented reliability update for Windows Server 2019 that addresses this scenario in the same manner as the improvement described for KB5126052.

    I hope this information is helpful. If you have any further questions, please feel free to reply in the comments.

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