I am using windows 10 and have re-installed Office 365. Since new installation I cannot open Outlook and have the foolowing message

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Microsoft Outlook
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Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The operation failed.
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OK  
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Hi,

Please first try starting Outlook with /resetnavpane switch and check if it will fix the issue. To do this, press Windows key + R to open the Run command, type outlook /resetnavpane and press Enter.

If above doesn't fix the issue, please try to adjust the file permissions for the Outlook data file that is in use and grant yourself Full Control permissions. To do this, please follow:

1. Browse to the file location that your Outlook data files are stored. By default, the path is:

C:\Users\username\AppData\Local\Microsoft\Outlook 

2. Right click on the Outlook data file (pst or ost) and choose Properties.

3. Switch to the Security tab, click the Edit button.

4. Select your user account and grant yourself the Full control permission.

5. Press OK until all dialogs are closed.

6. Start Outlook again.

Hope this helps.

Regards,

Steve Fan
TechNet Community Support