Outlook - set of folders cannot be opened - unable to fix this error via any method

Question

Hello,

i have an issue i've been unable to resolve for a few weeks, maybe even months now.

I was setting up a new All-in-One PC for an employee at a company we do IT support for. The setup went without a problem, he has Windows 10 OS and a Microsoft 365 Business Standard license.
A week or two go by and he informs me hes getting the known error when opening Outlook - The set of folders cannot be opened. To simplify, I decided to create another mail profile. This seemingly resolved the issue but I get another call from him a few days later saying the same problem has occured. We repeat the process and create a 3rd email profile. The same error pops up again, even sooner (maybe a day or two). The most peculiar thing is (he has 3 or 4 profiles at this point) that if I keep swapping between the profiles randomly and trying to start Outlook, lets say 1 in 20 times it actually starts up.
So I start troubleshooting the issue with everything I could find on google.

A list of possible solutions I've tried to far:

1. Starting outlook in safe mode - still does not start
2. Disabling add-ins - did not help
3. Reinstalling Office365 - did not help
4. Repaired Office365 - did not help
5. I believe i've tried some other repair/scan tools but nothing ammounted to anything

At this point I figured it might have to be something on his domain profile, so we delete the local profile and recreate it, the error still appears.

We replace his new PC with his older one on which everything works without any problems. We try creating a local account on his co-workers account, Outlook works fine there.

So a few days ago I decide to just reinstall the windows again hoping it would solve the issue (I did the reset with keeping the personal files). I install Outlook, it opens up. To test it out I close it down and try to re-open it - im hit with the error. I create a new profile again and manage to open Outlook exactly once, when i close it down and reopen the error hits me again. Just to make sure i repeat the process a 3rd time, same result - so in short whenever i create a new profile i manage to start up Outlook exactly once before the error appears.

At this point I'm out of ideas on what to try, I plan to bring another machine, domain join it and create his profile on it to see if the problem repeats - so far this only happens on 1 machine, on 2 others in the same domain it works fine.

Is there any reason this could be a hardware issue? Because thats the only thing that somewhat makes sense to me altho on the other hand I can't imagine it being hardware related. The OS and O365 are all updated.

Thanks for any advice or input in advance

Answer 1

Had the same problem

These steps fixed it.

If updating the Outlook application was not able to fix the error in Outlook “the set of folders cannot be opened” then you have to recreate the Outlook email profile. This method has helped many users to fix the error. 

1. Go to the Windows search bar and type regedit. This will launch the Registry Editor.
2. Then, navigate to Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\16.0\Outlook\Profiles (Outlook 2019,2016)
3. Now delete all the folders listed under Profiles.

Note: If you are using a different version of Outlook this will change as follows. Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Office\15.

  4. Restart the computer.

  5. Relaunch Outlook and recreate your email profile.

Answer 2

Hi, BS Admin

According to your description, thanks for your attempts for narrowing down the issue for us.

Could you please allow us to confirm that if you have tried for Repair Outlook Data Files (.pst and .ost)?

Also, please be kindly to have a check on the OWA - Outlook Web App to see if it works fine via the website.

In addition, please turn-off the VPN or firewalls temporarily and have a check if have you have these.

What's more, please capture the screenshot of the error and detailed version to us for further troubleshooting.

Please feel free to contact us if there's an update.

Regards,

Zed

Answer 3

Hello Zed,

i have tried repairing the .pst and .ost files, it did not help.

I can confirm that the OWA works fine.

There are no VPN connections.

Directly translated the message reads :

Microsoft Outlook could not be started. Outlook window cannot be opened. THe selection of folders cannot be opened. An unexpected error occured.

EDIT: this is the english verison of the error message

The build and version number in the screnshot above.

Answer 4

I recently installed Office 2021 on a Windows 11 machine. Outlook is crashing constantly with the exact same settings that run fine on a Windows 10 machine. I spent hours waiting for Microsoft support that now is only offered through chat. After spending 1.5 hours on line with the support tech (cncelled 2 prior attempts after waiting for 1 hour each with no agent coming into the chat) logged on into my computer he could not fix it. I then bought and downloaded Office 365 and get the same errors either crashing or "cannot open the set of folders the server is not available contact your administrator". I run a small business and don't have an administrator. I have used Office 2016 for years without these issues. I don't see how people are dealing with Microsoft anymore. No phone number to call even though I just bought both Office 2021 and 365. You have to sit on chat and then the problem cannot be resolved. I have a couple of Apple products and you get competent support right away on the phone. I can typically manage all technical issues myself and have written software. I am in disbelief as to how poorly written and supported Office 2021 and 365 are. The chat support agent scheduled a call for me with a Microsoft engineer in 1.5 weeks which he said was the earliest time one was available. How am I to run my small company with no Outlook which I use solely for e-mail. Bought 2021 and 365 are obviously defective products and no way to even get a refund or talk to anyone? I know that 365 has a telephone number but why bother for hours of wasted time? Microsoft has truly become a disgrace that hides from its consumer customers. Try to start a technical support request and see how difficult they purposely make it.