The operation couldn’t be completed. (com.apple.accounts error 3.)

I am experiencing the same issue for the past four days. I am running macOS Sequoia 15.6.1, and the built-in Mail app can no longer add my Exchange account after completing two-factor authentication.

The error shown is:

“The operation couldn’t be completed. (com.apple.accounts error 3.)”

Important to note: I am using a Microsoft 365 F3 license, and this setup has always worked without any issues until now. Outlook on the web and on my iPhone still work normally — only the macOS Mail app is affected.

Things I already tried:

• Removing and re-adding the account
• Restarting the Mac
• Resetting Mail- and Account-related system settings

Since the failure occurs only on macOS Mail, it appears to be an issue with the latest macOS build and Exchange authentication.

Any assistance or official statement would be appreciated.

Thanks!

Today, my Exchange Account stopped working in the Mail app on macOS 26.1 (25B78). I have tried to re-add it, but I am getting an error after successfully completing two-factor authentication. The web and iPhone clients work as usual. Please advise.
The operation couldn’t be completed. (com.apple.accounts error 3.)

As you explain it this way it looks logical. But I don't understand why it worked for a long time and caused troubles since a few days. What changed?

In my case it looks like it has something to do with the license.

The user who had the problems used a f3 license. I added an exchange license to it and now I'm able to setup the mail account in apple mail.

and yesterday another user told he had problems using apple mail. I also added a exchange license to the user, but he has not yet confirmed if the problem is solved now.

But I think think microsoft changed something on the license.

When checking in the azure admin portal I can also see that imap is disabled for f3. For exchange licenses it's enabled. So I'm not sure if this was the same before the problems arised.

Hi @Ralf

Thank you for posting your question in Microsoft Q&A.

We understand that your business account cannot be added to Apple Mail.

Based on my research, this issue may be related to a known issue that Microsoft has acknowledged regarding Microsoft 365 email accounts disconnecting from Apple Mail. You can find more details here: Reconnecting your Microsoft 365 account to Apple Mail - Microsoft Support 

You could try to follow these steps to troubleshoot it: 

Re-enter Your Login Credentials 

When prompted, click Edit Settings in the Apple Mail app and re-enter your login credentials. 

If you don’t see this message in Apple Mail: 

Open the Settings app. 

Go to Apps -> Mail -> Mail Accounts. 

Re-enter your login credentials. 

Update Your Microsoft 365 Account in Apple Mail 

1.Delete Your Microsoft 365 Account 

Open the Settings app. 

Tap Apps -> Mail. 

Tap Mail Accounts -> Exchange. 

Scroll to the bottom and click Delete Account. 

2.Add Your Microsoft 365 Account Again 

Open the Settings app. 

Tap Apps -> Mail. 

Tap Mail Accounts -> Add Account. 

Select Microsoft Exchange and enter your credentials. 

Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution. 

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".      

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.