[Reproducible] Excel crashes with Rtc.dll / 0xc0000005 on both Beta and Current Channel

Excel/Office crash that previously occurred on Beta Channel is now also happening on Current Channel

I previously reported the same issue.

At that time, I was using the Microsoft 365 Beta Channel, so I suspected that this might be a regression specific to a Beta build.

However, the situation has now changed.

I completely formatted and reinstalled Windows, then performed a fresh installation of Microsoft 365. I am now using the Current Channel, but the exact same issue is still occurring.

Because of this, it is becoming difficult to consider this as simply a Beta Channel issue.

Relevant videos : https://youtu.be/t1eQi1TuRjo

Current environment

• Fresh Windows installation after full format
• Fresh Microsoft 365 installation
• Microsoft 365 Current Channel
• Excel version: 16.0.20430.20092
• Crashes occur when working with Office files stored in OneDrive/cloud locations
• The behavior is very similar to the Excel and Word crashes I previously experienced on the Beta Channel

In the case of Excel, Windows Event Viewer records a clear application crash.

Windows Event Viewer crash information

• Event ID: 1000
• Faulting Application: EXCEL.EXE
• Application Version: 16.0.20430.20092
• Faulting Module: Rtc.dll
• Module Version: 16.0.20430.20092
• Exception Code: 0xc0000005
• Faulting Offset: 0x000000000024177e
• Excel Path: C:\Program Files\Microsoft Office\root\Office16\EXCEL.EXE
• Module Path: C:\Program Files\Microsoft Office\root\Office16\Rtc.dll
• Integrator Report ID: 44068f90-3fab-4746-9694-ed9d08c42231

The exception code is 0xc0000005, which indicates an Access Violation, and the faulting module is Microsoft's own Rtc.dll located inside the Office installation directory.

Important point

This is not occurring on an old Windows installation that has been used for a long period of time.

On September 24, 2026, I completely formatted and reinstalled Windows, then installed Microsoft 365 from scratch. The same problem was reproduced immediately on the Current Channel.

For that reason, it is difficult to explain this issue simply as being caused by old Office caches, remnants of a previous installation, or an existing Beta Channel environment.

I previously encountered the same problem while using the Beta Channel and already submitted feedback to Microsoft.

However, I have not received any specific response, acknowledgement of investigation, or information about the status of the issue.

Now that the same type of crash is occurring on the Current Channel, this no longer appears to be limited to Beta builds.

I would like Microsoft to clarify the following

1. Is the 0xc0000005 crash involving Rtc.dll a known issue?
2. Has Microsoft received other crash reports with the same crash signature?
3. Why does the same issue occur on both Beta Channel and Current Channel?
4. Are there any known issues involving Rtc.dll and Office cloud/OneDrive file handling or collaboration features?
5. Is this issue currently under investigation?
6. Is there any planned fix or known workaround?

Most importantly, this issue has now been reproduced on a completely fresh Windows installation with a fresh Microsoft 365 Current Channel installation.

Because of that, I would appreciate it if this issue could be investigated based on the actual Rtc.dll crash information rather than only suggesting generic troubleshooting steps such as reinstalling Office or Windows.

If other users are experiencing the same issue, it would also be useful if they could share the following information from Windows Event Viewer:

• AppVersion
• ModuleName
• ModuleVersion
• ExceptionCode
• FaultingOffset

I would also appreciate clarification from Microsoft as to whether this issue is currently being investigated.

Full Event Viewer crash details

Event ID: 1000 Source: Application Error AppName: EXCEL.EXE AppVersion: 16.0.20430.20092 AppTimeStamp: 6aafbf1b ModuleName: Rtc.dll ModuleVersion: 16.0.20430.20092 ModuleTimeStamp: 6aafb413 ExceptionCode: c0000005 FaultingOffset: 000000000024177e ProcessId: 0x3704 ProcessCreationTime: 0x1dd4bf9b3547dac AppPath: C:\Program Files\Microsoft Office\root\Office16\EXCEL.EXE ModulePath: C:\Program Files\Microsoft Office\root\Office16\Rtc.dll IntegratorReportId: 44068f90-3fab-4746-9694-ed9d08c42231