How to move Classic Outlook to SAME on new computer while retaining all calendar data

Question

How to move Classic Outlook to SAME on new computer while retaining all calendar data

Bec N 20

My old laptop has Classic Outlook. I use it only for the calendar (which also serves me as a form of diary), and prefer it over the new Outlook (for now). I installed the Officesetup.exe on the new computer (I had downloaded the Classic version), but I'm not sure how to get the correct data to transfer. File Explorer on the old computer shows a variety of .pst files, but, a few years ago, thinking I knew what I was doing, I accidentally deleted a file (not sure which one/type) and lost my many years of calendar.

I have a file called Outlook.pst, one called My Calendar.isc, several files by date called "Outlookbackupmmddyy.pst" that I created.

I'm probably being overly cautious because I was SICK when I lost my calendar before. Thankfully a local guru was able to dig down and get it reloaded.

Another issue - the new laptop lists 4 calendars in the left panel (see image). Holidays show up 2-3 times because of this, I guess. Again, I only want my one calendar with all the entries displayed like they are on the old computer.

Please help! And thank you!

At a Loss in the Midwest,

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Bec N 20 Reputation points

2026-02-11T20:57:47.0233333+00:00

I don't think I mentioned two other files I have - "My Outlook Data File(1).pst" and "My Outlook Data File(2).pst"

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Bec N 20 Reputation points

2026-02-11T20:57:47.0233333+00:00

I don't think I mentioned two other files I have - "My Outlook Data File(1).pst" and "My Outlook Data File(2).pst"

Answer 1

Alice-N 7,570 Microsoft External Staff Moderator

Dear Bec N,

Please note that our forum is a public platform, and we will modify your question to hide your personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

Thank you for reaching out to the Microsoft Q&A forum. I understand you are having problem with moving Classic Outlook to a new computer while keeping your full Calendar/diary history, and the new computer is showing multiple calendars (with Holidays duplicated). I am happy to assist you. Please follow these steps:

On the new PC, use Classic Outlook to open each PST until you find the one that contains the full calendar history
- File > Open & Export > Open Outlook Data File, then select Outlook.pst (repeat for My Outlook Data File(1).pst, My Outlook Data File(2).pst, and each Outlookbackupmmddyy.pst until you locate the PST that contains the complete Calendar). This mounts the PST so you can verify the Calendar content before you import or move anything.
Remove the extra calendars shown in the left pane by closing extra PST data files (this does not delete your data)
- When you open multiple PSTs, each PST can show its own Calendar in the left pane. Close the PSTs you don’t want visible: in the folder pane, right-click the Outlook Data File name and choose Close “Outlook Data File”.
- If a calendar is a separate calendar you created (not the primary), you can remove it from Outlook’s calendar list using Microsoft’s “Delete a calendar” guidance (primary calendar cannot be deleted).
If the “My Calendar.isc” is driving duplicate holiday/events (calendar subscription), remove the subscription instead of deleting your main calendar
- Outlook.com / web: Calendar > Settings > View all Outlook settings > Calendar > Shared calendars, then remove the calendar under “Calendar subscriptions”.
- If you need to remove calendars from Outlook.com directly, remove a calendar from the calendar list via More options > Remove.
- If you only have a one-time calendar file (.ics/.vcs) to add (not subscribe), import it via File > Open & Export > Import/Export > Import an iCalendar (.ics) or vCalendar file (.vcs).

Fix duplicated Holidays

Delete duplicate calendar items in bulk (works for duplicated Holidays too)
- Calendar > View > Change View > List, then sort by Subject, Ctrl-select duplicates, Delete.
Remove Holidays category items (if Holidays were imported multiple times)
- Classic Outlook Calendar > View > Change View > List, then arrange/sort by Categories, select Holidays entries, Home > Delete.

If the correct PST opens but calendar is missing items or errors appear

Repair the PST with Microsoft Inbox Repair Tool (scanpst.exe), then re-open the PST and re-check the Calendar.
Do not attempt to import calendar from PST in “new Outlook” .Importing mailbox/calendar using a .pst is not supported in new Outlook; please use Classic Outlook for PST calendar recovery/migration.

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Bec N 20 Reputation points

2026-02-12T20:42:43.0933333+00:00
I use this only for myself at home.

I'm trying to work through your answer. Questions that come up include:

Is there a difference between an Outlook Data file, my Outlookbackupmmddyy files, Primary calendar, and the backup pst files that I created.

None of the calendars in the left pane are grayed out, however the one that does not give an option for "delete" in the drop-down box shows only multiple holidays and recurring (annual) events. So is it the primary?

I imported my latest pst backup, which at first glance appears to have all my data but the category colors are not there. Maybe the repair tool takes care of this when I get that far? I don't understand about the pst "mounts". Is this now my main primary calendar?

I've read through the steps and keep getting stuck.
Alice-N 7,570 Reputation points Microsoft External Staff Moderator

2026-02-13T04:11:02.1666667+00:00
Dear Bec N, Thank you for trying out the previous steps. I'm sorry that it might be a bit confusing for you. To answer your question one by one:

Outlook Data File (.pst) / Outlookbackupmmddyy.pst / My Outlook Data File(1).pst / (2).pst. These are all PST data files. A PST can contain mail, contacts, and calendar items. The dated “Outlookbackupmmddyy.pst” files are simply additional PST copies created at different times. PST files can be moved to a new computer to retain information (but they do not transfer account settings).

“Primary calendar”. The primary Outlook calendar cannot be deleted; only additional calendars you created/opened can be removed.

“Mounts” (what it means). “Mount/open” means Outlook is opening a PST so you can view its contents (including its Calendar) without merging it into another calendar automatically.

My Calendar (.isc / subscription scenario). If “My Calendar.isc” represents a subscribed internet calendar, it can cause duplicate entries/holidays when the same calendar is also imported elsewhere.

Please try these additional steps:

First determine whether PST is even the right migration path. POP accounts store mail/calendar data in a .pst, while Outlook.com / Microsoft 365 / Exchange / IMAP use an .ost (server‑synced), meaning the calendar should come back if adding the account on the new PC.

Create one clean export from the old PC. Export mailbox data (including Calendar) to a new .pst using the classic Outlook Import/Export wizard. Please avoid exporting to OneDrive locations.

Import using “no duplicates / replace duplicates” options (prevents repeat Holidays/events). Import from a .pst into classic Outlook, and the Import/Export flow includes handling duplicates.

If any PSTs are stored in OneDrive, move them out before working with them PSTs inside OneDrive can cause sync/performance issues. Please copy the PST to a local non‑OneDrive folder and disconnect the OneDrive path in Outlook.

See: How to remove an Outlook .pst data file from OneDrive - Microsoft Support

See: Create an Outlook Data File (.pst) to save your information - Microsoft Support

If the Outlook profile on the new PC has multiple calendars, odd defaults, rebuild the profile. Creating a new Outlook profile using the profile picker / Outlook.exe /profiles, then re‑adding the account. See: Create an Outlook profile - Microsoft Support
Bec N 20 Reputation points

2026-02-13T20:49:56.6633333+00:00

Alice-N, it took me several hours over a couple of days to reach a successful outcome. I could NEVER have done it without your help! Some of it was by trial and error as I gained confidence.... and reread the steps I missed or misunderstood the first/second/third time around, even though your clearly-stated instructions were excellent. I am so grateful.

One visual disappointment is that the assigned categories did not come through. If you have a fix for that, please let me know. Otherwise, it appears at first glance that it WORKED! Thank you!
Bec N 20 Reputation points

2026-02-13T20:50:40.86+00:00

Alice-N, it took me several hours over a couple of days to reach a successful outcome. I could NEVER have done it without your help! Some of it was by trial and error as I gained confidence.... and reread the steps I missed or misunderstood the first/second/third time around, even though your clearly-stated instructions were excellent. I am so grateful.

One visual disappointment is that the assigned categories did not come through. If you have a fix for that, please let me know. Otherwise, it appears at first glance that it WORKED! Thank you!
Alice-N 7,570 Reputation points Microsoft External Staff Moderator

2026-02-15T03:25:54.4566667+00:00

Hi Bec N — glad the calendar data is back, the credit also goes to you!

To answer your question: The missing category colors usually means your Master Category List (the list that maps category names > colors) didn’t transfer, even though the appointments did. In Classic Outlook, run “Upgrade to Color Categories” (Data File Properties). This rebuilds the Master Category List from the categories already stamped on your items.

If you want to carry over your exact category set, you can also export/import them using a Categories.msg note (save a categorized Note as .msg on the old PC, then drag it into Notes on the new PC) and then run the same upgrade step.

Also note: new Outlook can open PSTs for mail, but Calendar/Contacts inside PST aren’t accessible there, so category/calendar fixes need to be done in Classic Outlook.

Hope my answer helps. Thank you for your amazing cooperation and have a nice day!

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How to move Classic Outlook to SAME on new computer while retaining all calendar data

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