Microsoft 365 login problem on latest Canary 27842

Hello.

I encountered a rather specific problem on the latest version of Canary 27842, although it did not appear immediately after installing this build, but only two days ago after updating Copilot, Microsoft 365 (via Store) where I'm an insider and Armoury Crate.

Namely, after these updates I lost connection to the Microsoft 365 service (information appeared about the loss of validity of credentials along with logging out of this service). Every attempt to log in to it now ends with error 2604 or 2603 (I am attaching screenshots), regardless of the Internet network through which I try to connect.

What's more, a similar situation also occurred on my laptop, which has the same problems. An attempt to reinstall the package did not solve the problem, similarly to an attempt to remove old credentials in the administration panel. All this happens despite correct login to the system via a Microsoft account, correct login to the Microsoft account in the browser and generally no other connection problems. The problem concerns only Microsoft 365.

I noticed something interesting because when I tried to run the Microsoft 365 troubleshooter, it did not uninstall, but when I tried to run it, I got information about the possibility of running the NVidia overlay, which is quite strange (this message generally only appears when starting games). Another thing is that when I try to verify the service account through the troubleshooter application - I get a message that the account cannot be verified.

I also tried:

• online package repair service from the Windows administration panel, but despite the completion of the process, the problem still exists;
• creating a new profile and trying to run the package on it (from the new profile) and this also did not work.  Trying to run the Microsoft 365 Connectivity Troubleshooter also fails with the message: "A problem occurred  A problem occurred while running the Microsoft 365 Network Connectivity Test Troubleshooter. Use the Get Help feature to search for a new solution." My wife's laptop also has the same problem with Microsoft 365 and she has also lost the ability to use the Microsoft 365 service (we have a Family license). This prevents her from working on important and urgently needed documents :(. I haven't noticed the problem - so far - on my mobile phone. I can use the program's functionalities in the mobile application I will add that yesterday I tried to solve the problem together with MS support (remote connection with support), but unfortunately we were unable to solve the problem. I was asked to pass on the information about it to the developer level.

Latest Update:

I looked at the problem from two levels tonight.

Generally, from the Microsoft 365 application level, e.g. when I launch Word, I get stuck on the inability to log in to this service. Trying to launch, for example, any Word file ends with a prompt to log in/no activation and generating the messages that I published in the 1st entry.

However, the situation is different when I launch Microsoft 365 Copilot. First of all, in this application I am logged in to the Office service, there is no prompt to log in (!!!). Secondly, I can create new Word files in it and work on them. Similarly, I can open and work with files in which I am indicated as the owner by name and surname. But when I try to open a file where I am not indicated as the owner, an error window pops up which I post with the following content: "This content is a potential security problem. Do you trust this content?"

[![](https://learn-attachment.microsoft.com/api/attachments/c9d8375b-8bc7-4fb0-bbb6-bf744b518357?platform=QnA "filestore.community.support.microsoft.com")  

When I click OK, this prompt pops up again, but at the same time there is information about a problem with connection 2604 and a login request to a Microsoft 365 Service/Word application, which still fails.

So If you look at screenshot below, I can open and work with any file where I'm a owner (owner - you/właściciel - Ty) but got problem with all files without this mark.

[![](https://learn-attachment.microsoft.com/api/attachments/1745108e-668b-4666-95f2-c80a9e79c7df?platform=QnA "filestore.community.support.microsoft.com")

If any of you have or had similar problems - please let me know. I kindly ask that the MS team take up the issue of fixing the failure as urgently as possible because the problem appeared after latest product update (Microsoft 365 Copilot) and unfortunately, it severely limits the functionality of the paid service

I will add one more note:

When I create a new file, e.g. Word on the desktop, I cannot open it from either Microsoft 365 or Microsoft 365 Copilot.

The first program asks for a login, the second displays the prompt I wrote about ("This content is a potential security problem. Do you trust this content?" - the file does not have my ownership assigned by default) although in the second I have the status of a logged-in person.

On the other hand, if I create a Word file in Microsoft 365 Copilot and save it to the desktop, then - as I wrote - I can work on it and open it from Copilot (where I have no problem with logging in/licensing), but from the regular Microsoft 365 level I get a login request, error 2604 or 2603 and activation block despite an active license on the Microsoft account.