Cannot sign in to Microsoft 365 Apps – Error: 7q6ch

Hi everyone, I need some help because I’ve been trying to fix this issue for several days without success.

The Issue

I cannot sign in to Microsoft 365 apps (Word, Excel, etc.) with my school account. When I try to sign in, I get the following error:

Something went wrong [7q6ch]. 

Correlation Id: 9cce4d22-711e-4e35-aa7a-19645d677507
Timestamp: 2025-09-08T10:31:26.000Z
DPTI: 61d393136e7d50a2d9ac1ed11266a043b8b2915fc70092c1ef88bfd4bc761df7
Message: An unexpected error occurred.
Tag: 7q6ch
Code: -2147023838

What I’ve Tried So Far

Reinstalled Windows 10

• Before reinstalling, I formatted my NVMe, so everything should have been clean.
• I switched from an Enterprise version to an official Windows 10 Pro installation.
• The reason for switching: the OEM Enterprise license key did not work on an officially installed Enterprise version, so I ended up installing Pro and purchased a new Pro license.
• During setup, I created a local account instead of signing in with a Microsoft account, hoping to receive updates for two more years so I wouldn’t have to switch to Windows 11, which I dislike.
• After reinstalling, I waited several hours for all Windows updates to download and install, so I don’t think the issue is related to missing updates.
• In Windows Settings → Accounts → Work or School, the page never loads, no matter what I try.

Reinstalled Microsoft 365 from multiple sources

First, I downloaded and installed it from the official Microsoft page.

• Then, I tried again from Office.com (as suggested), but the problem remains.
• Within Word, I also manually triggered the software updates multiple times, and the application restarted itself during the process each time, but the issue persisted.

Account access check

I can log in to my Microsoft account and use Office online without issues.

The installed desktop apps still do not allow me to sign in.

Signed out all old devices

In my account settings online, I signed out of all previous devices.

My current PC is the only active one.

Password reset

I changed my password, but the problem persists.

Official Response I Received

The administrators of my school confirmed my account works online, and that’s as far as their responsibility goes. They said the installer from Office.com should work, but it doesn’t. They cannot provide further support.

Possible Cause (Based on ChatGPT Discussion)

While discussing this with ChatGPT, I concluded that even though I formatted my SSD, switching from Enterprise to Pro might have left some remnants of the previous system, which could prevent proper sign-in and activation of Microsoft 365.

During the discussion, I also explored multiple advanced troubleshooting steps using PowerShell:

The issue was that the Microsoft 365 package installed on Windows 10 Pro could not authenticate with the system. The output of dsregcmd /status showed that AzureAdJoined, WorkplaceJoined, and related SSO states were all "NO" or incorrect. The Work or School page in Windows Settings never loaded, and the UserDataSvc and WpnUserService services either did not start or could not be set to start automatically. Previously, I had tried the official Microsoft 365 installer, signing out old devices through the Office portal, and a password reset, but these did not resolve the problem. In PowerShell, I first attempted to enable and restart critical services (UserDataSvc_c2e2a, WpnUserService_c2e2a) and remove previous Azure AD join tasks from Scheduled Tasks. I repeatedly ran dsregcmd /join and logged the entire process, including the output of dsregcmd /status, to track state changes. Frequently, the services would fail to start, or the join task would stop with error 0x80041326.

My Questions

Since I can’t get further help from my school’s support, I’d like to ask the Microsoft community:

How can I fully remove any remnants of the old system so Microsoft 365 apps work correctly?

What steps should I take to make sure the installation is clean?

Should I reinstall Windows again? If so, what’s the safest way to ensure no leftover configuration causes problems?

This is very important for me because I’m working on my thesis and need full access to Microsoft 365 apps like Word and Excel.

Thank you in advance for any advice!