Office Apps Crashing

How to Fix Word Crashing with Interop.Range.HighlightColorIndex

Algirdas Jasaitis Oct 1, 2026 869 views

Question details

Developers need a solution for a regression issue where Microsoft Word crashes when a script attempts to modify the text highlight color index upon exiting a content control.

How to Fix Word Crashing with Interop.Range.HighlightColorIndex

Product: Microsoft Word (Versions 2405 and 2406)
Device & OS: not provided
Scenario: Executing a C# VSTO add-in or Visual Basic macro that triggers the Interop.Range.HighlightColorIndex property during the Document.ContentControlOnExit event.
Observed behavior: Microsoft Word unexpectedly crashes and closes when the code executes in builds 2405 and 2406, whereas the exact same code runs perfectly in build 2404.

Before you start

Ensure all your working documents are saved and backed up, and verify that you have administrative privileges to perform Office version rollbacks or install updates.

Solution 1Recommended

Roll Back Office to a Stable Build (Version 2404)

Since the bug was introduced in builds 2405 and 2406, reverting to version 2404 is the most reliable way to restore macro functionality immediately.

Microsoft Word version-specific Interop issues can disrupt critical business operations. Rolling back your Office installation to the last known good configuration (build 2404) allows your C# VSTO add-ins and VB macros to function normally while you wait for an official patch.

Disable Automatic Updates

Open Microsoft Word, navigate to 'File' > 'Account', click on 'Update Options', and select 'Disable Updates' to prevent Word from automatically reinstalling the problematic build.

Open Command Prompt as Administrator

Click the Windows Start menu, type 'cmd', right-click on 'Command Prompt', and select 'Run as administrator'.

Execute the Reversion Command

Navigate to the ClickToRun directory by typing 'cd %programfiles%\Common Files\Microsoft Shared\ClickToRun' and press Enter. Then, run the Office Deployment Tool command to revert to build 2404 (e.g., 'officec2rclient.exe /update user updatetoversion=16.0.xxxxx.xxxxx' replacing the x's with the specific 2404 build number).

Roll Back Office to a Stable Build (Version 2404)

Temporary Workaround: This rollback is a temporary fix. Remember to re-enable updates once Microsoft officially resolves the HighlightColorIndex bug in a future release.

Solution 2

Check for the Latest Office Updates

Microsoft routinely releases patches for Interop and VSTO vulnerabilities. Checking for newer updates may resolve the crash if a hotfix has been deployed.

Solution 3

Report the Issue on Microsoft Q&A

Escalate the unresolved bug to Microsoft engineers and the developer community for deeper investigation and tracking.

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Try WPS Office for Stable Document Editing and Macro Execution

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Frequently Asked Questions

Why does changing HighlightColorIndex cause Word to crash?

This is a known version-specific regression bug introduced in Microsoft Word builds 2405 and 2406. It affects the Interop layer's stability when interacting with content control events, causing an unexpected application failure.

Is my C# VSTO code or VB macro causing the issue?

If your script executed perfectly in build 2404 or earlier, the crash is almost certainly due to the Microsoft Office update rather than a syntax error or logical flaw in your macro code.

How can I prevent Office updates from breaking my macros in the future?

You can disable automatic updates by opening Word, navigating to File > Account > Update Options, and clicking 'Disable Updates'. It is highly recommended to test new Office builds in a staging environment before deploying them to your entire business.

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