Outlook problem connecting to Exchange online mailbox

Question

Hello,

I have a problem with Outlook 365 configured with an Exchange Online mailbox in Windows 10, after working perfectly for several months, suddenly at random times, when Outlook is started, it will not connect (“Trying to connect” appears in Outlook status bar). In the event log the following event appears:

“The Exchange web service request GetAppManifest failed. The error code is 0. HTTP response code: 401
Additional Error Message: An unknown internal error occurred. The error code is 80004005”

The mailbox can be opened perfectly fine in a web browser (OWA) in the same computer, and Outlook 365 with the same account works fine in another (work) computer and on the user's phone.

I've verified the internet connection for the computer and it is working fine, there isn’t any firewall or antivirus installed other than Windows Defender (it’s a home computer). I tried to uninstall and reinstall Office 365 and recreate the profile but the issue persists.

Any ideas of what can be causing the problem?

Thanks,

Ricardo

Answer 1

Hi @RickiPeru ,

after working perfectly for several months, suddenly at random times, when Outlook is started, it will not connect

Any changes were made to the affected mailbox(es) right before the issue started?
In order to help narrow down whether the issue is caused by any third-party add-ins added in the Outlook client, it's suggested to try running Outlook in safe mode(Press Win+R, type "outlook /safe", press Enter.) when the issue occurs and see if Outlook can start properly.

and Outlook 365 with the same account works fine in another (work) computer and on the user's phone.

By this, do you mean the issue is now only affecting a particular account on a particular computer? If this is the case, based on my research on the error you shared above, it could be related to dns, please try running "Ipconfig /release" then "Ipconfig /renew" on the problematic computer and see if there would be any improvement.

Here's a thread which mentions the similar event log in the discussion for reference:
I have a user who has multi-factor sign in and outlook wont accept credentials
Please Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.

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Answer 2

We are experiencing this problem on terminal servers. Yes, logs occur periodically and Outlook becomes inoperable. When I restart the "Microsoft Office Click-to-Run Service", outlook becomes operational.

After collecting and examining the necessary logs, the Microsoft engineer entered 2 regedit records (SCLCacheOverride 1 and SharedComputerLicensing 1) and allowed time for testing. But errors continued to occur over time.

This annoying problem causes intense complaints from users and partially hinders work.

Orginal Language:

Bu problemi terminal sunucularında yaşıyoruz. Belirli periyotlar ile evet log oluşuyor ve outlook çalışmaz duruma geliyor. "Microsoft Office Click-to-Run Service" yeniden başlattığımda outlook çalışır duruma geliyor.

Microsoft mühendisi gerekli logları toplayıp inceledikten sonra 2 adet regedit kaydı (SCLCacheOverride 1 ve SharedComputerLicensing 1) girişi yaptı ve test için süre tanıdı. Fakat geçen sürede hata oluşmaya devam etti.

Bu can sıkıcı problem kullanıcılar tarafından yoğun şikayete neden oluyor ve çalışmaları kısmen engelliyor.