Share via

Transition from Office 365 to Office Pro 2021

Anonymous
2022-06-09T01:59:51+00:00

I have used MS Office on my desktop for many years.  I switched from a standalone version to Office 365 on my desktop a couple of years ago.  I have already purchased MS Office Pro 2021 and I’m getting ready to switch back to the standalone version.

I have two email accounts setup in Outlook, and therefore I have two ost files (they used to be pst files).  I assume there is one ost file per email account. One of the ost files is older and much larger than the other one.  I also access my two email accounts online at Outlook.com and the emails, folders, contacts, and calendars seem to stay synced automatically with my desktop Office 365.

I sometimes, but very rarely, use Excel and PowerPoint.

I’m not sure how to transition from O365 to Pro 2021. Do I just install the new Pro 2021 and it sees the O365 and transfers the ost files automatically?  Will it guide me in the process? Will I need to uninstall (delete) O365 when the transfer is complete?  Will all my emails and folders and contacts and calendars be in the new standalone Pro 2021 after I install it?

Since one of the ost files is many years old, when I switch back to the standalone version, should I start with a new ost file?  It seems like that would get rid of any old **** left over from many years of use.  Or would that be a bad idea? I really don’t have any idea what’s in an ost file. 

Thank you in advance for help you can give me before I start this process.

Microsoft 365 and Office | Install, redeem, activate | For home | Windows

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

0 comments

11 answers

Sort by: Most helpful
Most helpful Newest Oldest
  1. Anonymous
    2022-06-09T02:47:25+00:00

    Hello 365Patrick

    Hi, I'm Karl and will be happy to help you today.

    If this transition is occurring on the same machine then it's a simple matter of

    #1 - Uninstall '365

    #2 - Install '2021

    As far as Outlook goes, Outlook profiles do not get removed when you uninstall Office (Outlook). When you install '2021, it will use the same Outlook profile that was used by '365 or to put it another way, '2021 will start off from where '365 left off.

    As far as OST files go, it means that the accounts are configured using either IMAP or Exchange. There's no point with starting with a new OST file since the OST file is a mirror of what is contained on the server. If you want to reduce the amount of space used, change the amount of data that is maintained in the OST file by changing the slider tor the amount of data that is downloaded. Do that by going to

    <File> --> <Account Settings> --> <Email> tab

    Select the email account --> click on <Change.

    If you have any contact / calendar data stored in "This Computer Only" folders (am IMAP account), you will be well advised to export those folders so that you don't potentially lose that data. If Outlook cannot find / open an OST file, it will automatically create a new one, sync the subscribed folders with the server but the "This Computer Only folders will be empty (ergo the data in those folders will be lost).

    If the account is an Exchange account, all data (email, contact, calendar) is sync'd with the server

    Was this answer helpful?

    3 people found this answer helpful.
    0 comments
  2. Anonymous
    2022-06-09T18:03:49+00:00

    Patrick, your subscription does not end, that is unless you cancel 'turn off recurring billing' your subscription automatically renew.

    Was this answer helpful?

    2 people found this answer helpful.
    0 comments
  3. Anonymous
    2022-06-09T16:52:28+00:00

    RonBarker – Thank you for pointing out that I will need to cancel my O365.  If I decide not to wait until my subscription ends, I will definitely do the cancel thing.

    Was this answer helpful?

    1 person found this answer helpful.
    0 comments
  4. Anonymous
    2022-06-09T10:03:00+00:00

    Patrick, you first need to cancel your Microsoft 365 Office: https://account.microsoft.com/services  Click on cancel (for more information see: Cancel a Microsoft 365 subscription) Then follow Karl's post.

    Was this answer helpful?

    1 person found this answer helpful.
    0 comments
  5. VARADHARAJAN K 9,691 Reputation points Volunteer Moderator
    2022-06-09T09:00:17+00:00

    Office 365 32bit and office 2021 32bit both installed in same location.

    This week I installed office 365 on top of office 2021 without uninstalling office 2021

    After that I opened word application it opened in office 365 only.

    First re-enter product key of office 2021 on office 365 word application, and see what's happens

    Was this answer helpful?

    1 person found this answer helpful.
    0 comments