Microsoft Outlook 2010 "Cannot open your default email folders."

Hi,

There are reasons why you're experiencing this issue. This could be caused by .ost file corruption or Outlook running in compatibility mode. For us to isolate the main issue, we suggest that you follow the steps mentioned below and see if there's any changes:

Step 1: OST file corruption.

1. Remove old profiles that you do not use. Go to Control Panel > Mail > Show profiles.
2. Re-create an OST file. Follow the steps on this link on how to compact PST and OST files to eliminate deleted item space in Outlook.
3. If the same issue persist, we suggest that you create a new Outlook profile. Once done and the problem continues, it is most likely caused by Outlook running in compatibility mode.

Step 2: Outlook is running in compatibility mode.

1. Navigate to C:\Program Files (x86)\Microsoft Office\Office XX\Outlook.exe.
2. Right-click on Outlook.exe and navigate to Properties > Compatibility tab.
3. Uncheck the Run this program in compatibility mode box, click Apply and OK.
   

If you are unable to place Compatibility tab, do the following:

1. Navigate to Start > look for Program Compatibility Troubleshooter.
2. Start Program Compatibility Troubleshooter > select Next option to proceed.
3. Select Outlook XX from the list or programs and follow the steps of the Program Compatibility Troubleshooter.
4. Navigate to C:\Program Files\Microsoft Office\Office XX\Outlook.exe.
5. Right-click on Outlook.exe and navigate to Properties > Compatibility tab.
6. Uncheck the Run this program in compatibility mode box, click Apply and OK.

Let us know if this will help address your concern.

Will any emails, contacts, or data be lost by creating a new outlook profile?

Outlook is currently not in a compatibility mode and outlook can not be opened to compact files, tried manually doing it through Control Panel only to be meant with error code: 0x80040116.

When you actually compact PST and OST files to eliminate deleted item space in Outlook, it will only delete the unwanted items from each folder, it moves them to the Deleted Items folder, which is in the same file.

Meanwhile, we suggest that you try to repair your Outlook personal folder file. Also, disable virus scanner integration. Virus scanners which integrates themselves with Outlook are a known source of causing all sorts of send receive issues. Disabling your virus scanner’s integration with Outlook does not compromise your security as you’d still be sufficiently protected by the on-access scanner part of the virus scanner.

Update us with results for further assistance.

The only profile for Outlook is the one being used and currently having issues, can't really delete that.

Tried repairing the file, found some issues, repaired them.  Tried opening Outlook, same issue still.  Found the virus scanner integration, disabled that, retried the repair, no issues found, tried opening again, still the same issue.

Did some other research and attempts at getting back on Outlook as well and was constantly meant with it being unable to connect to the email server or be able to login.  It is a POP3/SMTP type email.  In case that info helps at all.

For now though I did create a new outlook profile, opened Outlook up, it works, I can view some of the emails from the other profile, however I need to find a way to either transfer over all contacts and folders or be able to open up the other profile.

And then I tried another thing for the old profile, somehow it messed up the new profile, now I can't access either of them. Created a new profile, emails that were accessible are no longer accessible. 

On top of that it can send emails, but it can't receive emails. They all just go to the other profiles even though those profiles can't be accessed.

It seems that we already performed multiple troubleshooting steps and the same issue still persists. For you to move or transfer all your contacts and folders, we suggest that you follow the steps on how to import email, contacts, and calendar from an Outlook .pst file. Detailed steps and information are all provided on the link.

If the issue still persists, don't hesitate to inform us and we'll be happy to further assist you.

       .SOLUTION FOUND.

I was about to uninstall and reinstall Microsoft Office, when I noticed a repair option in the 'Uninstall a Program' menu. I figured why not try it. Outlook is working fine now.