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Outlook 2016 shared mailbox - "Cannot expand the folder" error. RRS feed

  • Question

  • Hello!

    We use Office 365 pro (Outlook 2016), Exchange 2013 server.

    Some of our users have several Exchange mailboxes in Outlook - one primary and 3-4 shared mailboxes, these mailboxes are added in outlook as separate mail accounts.

    From time to time some of them catch a bug - one or two of shared mailboxes refuse to open with error "Cannot display the folder. Microsoft Outlook cannot access the specified folder location. The operation failed. An object cannot be found".

    When in Outlook going to File -> Account Setting -> Email,  I see that .ost file location of this shared mailbox points to .ost file of primary mailbox.

    So, at some point of time .ost file location setting of shared mailbox brokes down and begin to point to .ost file location of primary mailbox.

    This setting (.ost location) in outlook 2016 is always greyed out, so I cannot change it manually to correct .ost file.

    Maybe there is some fix from Microsoft to resolve such an issue?

    Thursday, May 25, 2017 8:25 AM

Answers

All replies

  • Will add - only solution now for us is to re-create outlook profile, but after several days/weeks the problem repeats.

    And it only occurs on "weak" five-seven years old PCs.

    OS on all the computers is the same - Windows 10 Pro x64.

    Thursday, May 25, 2017 9:39 AM
  • Hi,

    Do you have full access permission to these shared mailboxes?

    By "these mailboxes are added in outlook as separate mail accounts", do you mean these mailboxes are added directly in your Outlook via File > Info > Add Account?

    Do you have Auto-Mapping enabled for these shared mailboxes? If so, please try to disable Auto-mapping for these mailboxes and then see if this issue will happen again.

    Regards,

    Steve Fan


    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Friday, May 26, 2017 7:26 AM
    Moderator
  • No, users have no access permission to these mailboxes; they are added directly to outlook via File > Info > Add account  as separate mail accounts with own passwords.

    AutoMapping has no sense cause user's accounts have no full access permission to shared mailboxes, they are not mapped automatically.

    Friday, May 26, 2017 8:45 AM
  • Hi Paul,

    Thank you for the update.

    >>No, users have no access permission to these mailboxes; they are added directly to outlook via File > Info > Add account  as separate mail accounts with own passwords.

    By "own password" do you mean the own password of the users who want to access the shared mailbox? By default, this will require Full Access permission to add the mailbox as separate Exchange mailbox in this way.

    If I've misunderstood something, please feel free to let me know.

    Regards,

    Steve Fan


    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Thursday, June 1, 2017 9:12 AM
    Moderator
  • Hi Steve,

    It's the password of shared mailbox's account, not the user's password.

    Thursday, June 1, 2017 10:16 AM
  • Hi Paul,

    Thank you for the update. Are the users' mailboxes on the same Exchange server with the shared mailboxes? If this is the case, I'm afraid unexpected error may happen when accessing multiple Exchange mailboxes in the same Outlook profile. Outlook 2016 let you add your delegate’s account to your own profile and lets your delegate add your account to their profile. However, although there is no warning message or error, this profile configuration is not supported. It's recommended to grant delegate permission to the shared mailboxes and then add these shared mailboxes as additional mailboxes which differs from a second account.

    See the following Microsoft KB articles for more information:

    https://support.microsoft.com/en-us/help/981245/issues-that-can-occur-when-you-add-multiple-exchange-accounts-in-the-same-outlook-profile

    https://support.microsoft.com/en-us/help/291626/how-to-manage-multiple-exchange-mailbox-accounts-in-outlook

    Regards,

    Steve Fan


    Please remember to mark the replies as answers if they helped.

    If you have feedback for TechNet Subscriber Support, contact tnmff@microsoft.com.

    Friday, June 2, 2017 4:07 AM
    Moderator
  • Each question and answer of the above string had applied to my situation so far, except that I did not see a direct response from Paul as to whether or not the above accounts were on the same Exchange Server (they are in my situation). So, I checked out the links.

    What worked for me: Removing the separate shared account, then re-adding it by selecting Change for my main preexisting account and selecting More Settings > Advanced tab > Add, as described on the link.

    Thank you, Steve Fan - I gave this answer a vote!

    Thursday, August 10, 2017 4:24 PM
  • Just spent a couple hours researching the error "Unable to expand folder....file is not a valid ost". I was adding a shared mailbox as if it were a new account. This results in the creation of a 0kb OST file named exactly as the E-Mail address it represents. You will never be able to open the folder in the navigation pane and you can't even view the files properties...

    The solution was to delete the new profile, and add the account to my existing, working profile. As Tek_Dr stated: add the shared mailbox under Account Settings->Change->More Settings->Advanced tab. Works great now.

    Monday, September 18, 2017 2:50 PM
  • I have this problem 2. Mainly only on one of the shared mailboxes (occasionly not as often another one). Really annoying when it's a part of your job and you need it. But the best thing is this only happens to me. Other users with this Inbox aren't affected, go figure grrrr.
    Monday, October 15, 2018 9:05 PM
  • Also I am the only one with this issue with the shared mailboxes
    Wednesday, October 17, 2018 9:23 PM