Outlook 2019 Default Data File Error (PST/OST)

Nate Thibault 26 Reputation points
2020-08-18T16:41:25.097+00:00

I am having an issue changing my default data file, when I try to make the one I want default I get an error saying:

The selected Outlook data file (.pst) format cannot be used. Outlook data files (.pst) must use the same format as offline Outlook data files (.ost). Select a matching Outlook data file (.pst) or turn off cache mode in the Account Settings.

The account I am trying to make default is a .ost so I do not understand why its telling me it can not be used. I have a total of 4 accounts, three are .ost and one is an exchange server account (which is the one selected as the current default). Therefor I only have one account that I can turn cached mode off for, and I did turn it off but I am still getting the same error.

Any idea?

Outlook Management
Outlook Management
Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Jade Liang-MSFT 9,956 Reputation points Microsoft Employee
    2020-08-19T09:50:22.547+00:00

    I have a total of 4 accounts, three are .ost and one is an exchange server account.

    As I know , .ost file usually be used to data files for IMAP accounts and Exchange accounts. So, are your three accounts IMAP accounts?

    If this is your case, according to my tests , I configured several IMAP accounts and Exchange accounts in one Outlook profile, and found that in this case, exchange account data file will always be set as the default data file . When changing other data files as the default data file, we will get the same error prompt as you. And this could be reproduced in different versions of Outlook such as Outlook 2016 and Outlook 365. So, I’m afraid this issue may be by design.

    If you actually want to use these accounts in one Outlook profile and change the default data files, as a workaround, you can try to add your exchange account again and turn off your cached exchange mode in the control panel when you just add your exchange account. For more information, please check this article: Set Another Data File as Default When Using an Exchange Account. (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.)

    What is also need to be mentioned is that above operations are effective when you firstly change your default data file, but you would face the same issue once you change your default file back to Exchange account again.

    Besides, it is usually suggested for users to add different accounts in separate Outlook profiles to avoid interference between multiple accounts.

    Hope above information is helpful to you.

    Update:

    What your saying is make sure the exchange account is not in cached mode at the time it is readded to the Outlook profile?

    Yes, as mentioned before, you could refer to the steps in this article Set Another Data File as Default When Using an Exchange Account to change your default data files. (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.)

    I just do not want my "default landing inbox" to be the exchange account.

    What's the exact issue you are facing with right now? As I know, changing default data file usually will not change the store location of those emails in Outlook which other users send to your IMAP and Exchange Accounts. So you wouldn’t change the mailbox’s Inbox even if you change your default data file from one to others. Please ensure if this solution meet your need before you change your default data file. For more information, please check the information in this article: Changing the Default Data File. (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.)

    If there is any misunderstandings, please feel free to let me know.

    If the response is helpful, please click "Accept Answer" and upvote it.

    1 person found this answer helpful.
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  1. Nate Thibault 26 Reputation points
    2020-08-19T17:52:34.517+00:00

    Yes, all three of my other accounts are IMAP.

    It does seem this issue only started after I added the exchange account a year ago so that would make sense. I upgraded from 2016 to 2019 and the problem still exists as well.

    What your saying is make sure the exchange account is not in cached mode at the time it is readded to the Outlook profile? I will never want the exchange account to be my default in the future anyway. I will try removing all the accounts from my profile and add them back one by one. Should I add the exchange account last after all the IMAPs? I just do not want my "default landing inbox" to be the exchange account.

    I am not sure why you would want multiple profiles in Outlook, I thought the whole point was to have all your email accounts in the same window?

    I wonder if this is what has been causing Outlook to crash when syncing folders, if I leave Outlook open for 8+ hours eventually it just hangs up on syncing. When I close Outlook when it gets stuck syncing folders it will not restart, the icon is greyed out in the notification area as well as in the task manager and I have to End Task to get it to relaunch. This problem followed me from 2016 to 2019 as well.

  2. Zenifer Smith 10 Reputation points
    2023-06-08T17:39:53.85+00:00

    Hi Nate Thibault,

    To fix the Outlook 2019 default data file error, follow these steps:

    1. Open Outlook and go to 'File' > 'Account Settings'.
    2. In the 'Data Files' tab, note the location of the desired .ost file.
    3. Close 'Account Settings' and exit Outlook.
    4. Open 'Control Panel', search for 'Mail', and select 'Mail (Microsoft Outlook)'.
    5. Choose your profile, click 'Properties', and go to 'Data Files'.
    6. Select the desired .ost file and click 'Set as Default'.
    7. Save changes, close all windows, and restart Outlook.

    After following these steps, restart Outlook to see if the error persists. Hopefully, this solution allows you to set the desired .ost file as the default data file without any issues.

    If the problem continues, please share additional details about your Outlook setup, including recent updates or changes made. This information will help me troubleshoot the problem more effectively and provide you with tailored assistance.

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  3. Hristian Carabulea 0 Reputation points
    2024-02-13T21:38:44.5066667+00:00

    I had this problem with the gmail account in Microsoft Outlook, but only the version which came with Microsoft Office. Not the new (free) Outlook.

    After following the previous instructions, the problem remained.

    The solution I found to work is:

    • I closed Microsoft Outlook
    • I moved the gmail (in my case) .ost file somewhere else - I did not delete it.
    • I opened Microsoft Outlook
    • Microsoft Outlook created another .ost file, for gmail in this case
    • Then I applied the advice above, which worked this time.
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