M365 PST-Import
Posted by joghurt_mit_der_ecke@reddit | sysadmin | View on Reddit | 13 comments
Hi,
I'm tearing my hair out at the moment because I'm not getting anywhere. Maybe one of you can help me.
I am currently trying to import mailboxes (which I have exported as PST files from our Exchange server) into Exchange Online via the Microsoft Compliance (Purview) Center.
I have checked the following: - The admin user with whom I want to perform the import has the import/export rights. - The upload via azcopy works without any problems. - The PST file is not corrupt. - The PST file is only 2GB in size. - The mapping file (CSV) is correct. - The user mailbox into which I want to import the PST file has a valid license (Microsoft 365 Business Premium) and the mail address is correct.
The check of the PST file also works without any problems and I can start the import via the "Import in Office 365" button.
The import job then runs for a while and after a few hours shows that it has failed. If I then download the log file, it only says that the import has failed and the only error message I'm getting is "Import Status: Failed" and "Error: Unknown".
Unfortunately, I don't know what to do. What am I doing wrong?
Thank you very much!
Technical-Device5148@reddit
Hi, i also have this same issue, raised something to MSFT about it... but in standard MSFT fashion, it's not going great.
joghurt_mit_der_ecke@reddit (OP)
Thats strange...
I did the migration last weekend, but in the end I used a Third Party Software (CodeTwo - no advertising!), because I wanted to upload the mailboxes earlier and only upload the remaining mails (since 2025) at the weekend --> Delta Migration
Worked really well, but but the software is not free.
Technical-Device5148@reddit
We use C2 for our Cloud Signatures tbh, i'm still waiting to hear back if we can have this included in our License
titlrequired@reddit
I’m having the exact same issue, I thought it was weird as I know the pst files are fine but it only happened with the most recent task (recreated and retried the process), have already imported 3TB for this client, with hardly any skipped items.
As these were the last ones I just imported them directly to the mailbox through outlook.
Worth opening a support case I think as seems to be a wider issue.
joghurt_mit_der_ecke@reddit (OP)
Thanks for your response. Now I'm a little reassured, because I was so confused that it was not working.
titlrequired@reddit
Well me too but I just figured 🤷♂️ Microsoft innit.
If it had been earlier in the project I was on I would have investigated more so I guess it’s fate I happened to see your message, if you believe in such things. Which I don’t.
joghurt_mit_der_ecke@reddit (OP)
I opened a ticket with Microsoft. I'll let you know as soon as I have some news.
titlrequired@reddit
Did you get anywhere?
joghurt_mit_der_ecke@reddit (OP)
Ah yes, thanks for the reminder.
So I had three remote sessions with Microsoft and two times we were not going anywhere and the import jobs failed without a helpful error message.
Then we connected to Exchange Online via PowerShell and found out that there were two profiles with the same mail address (one was softdeleted but still there). The Microsoft employee told me that would be the problem but after deleting the softdeleted profile it didn't either. But at the same time we tried to import the same PST-File in a newly created profile and that worked.
So I will wait 30 days till the old profile is harddeleted (if it's still there??) and try again. But as I said the import in the newly created profile worked so that's why I don't feel like talking to Microsoft again at the moment.
But it's really annoying that there are no useful error messages...
titlrequired@reddit
By profile you mean the what? The azure storage the psts go into?
Kind-Elk-7604@reddit
Hi, check out these helpful guides this might help you.
· https://learn.microsoft.com/en-us/purview/importing-pst-files-to-office-365
· https://learn.microsoft.com/en-us/purview/use-network-upload-to-import-pst-files
I hope these blogs can solve your issue. There is an easy way you can import PST files into Office 365, Try Stellar Migrator for Outlook, this tool can directly import PST files into Office 365 by using modern authentication method, it will save your time by avoiding the complexity of manual solutions.
OrganicSciFi@reddit
Why not just copy using Outlook? Is there more than one pst?
joghurt_mit_der_ecke@reddit (OP)
Yes there are around 70 PST-Files.