Background
I usually refrain from writing posts on issues where I haven’t been able to fully reproduce them in my lab but enough people seem to be having this issue that it would be good to spread the word should another person find themselves afflicted by it. I’ve seen this issue happen in two different environments & then found out via the forums that several other people have run into it as well.
Issue
I was working with a customer who migrated from Exchange 2007 to Exchange 2013. After decommissioning the 2007 servers, all the Exchange 2013 mailboxes started getting the infamous “The Microsoft Exchange Administrator has made a change that requires you quit and restart Outlook” prompt.
This seemed odd because Exchange 2013 was supposed to all but eliminate those prompts. While it did eliminate the prompts when the RPC Endpoint (Server Name field in Outlook) changed, there are still other scenarios that could result in this prompt (please see reference links at bottom of post for a detailed history). One such thing relates to the Public Folder Hierarchy.
In this customer’s scenario, I determined that the “PublicFolderDatabase” attribute on every Exchange 2013 Mailbox Database was set to a value resembling the screenshot below:
In this case, the decommissioning of Exchange 2007 & its Legacy Public Folders was not done correctly (same issue probably would have occurred if it were 2010). The Public Folder Database was showing up as a deleted object in AD. So the result was that the Outlook clients were trying to access Public Folder information but were reacting in a way that resulted in the frequent prompt to restart Outlook.
The resolution in this case was to drill down to the properties of the Mailbox Database in ADSIEDIT & set the value of “msExchHomePublicMDB” to be blank. Afterwards, a restart of the Information Store Service resolved the issue.
Additional Info
Not long after this issue, I was contacted by a Consultant I know who encountered the exact same issue. After an improperly performed Exchange 2007 migration, the Exchange 2013 mailboxes were getting prompted to restart Outlook. That environment also had Mailbox Databases that were pointed to a deleted object for their default Public Folder Database. Clearing the value & restarting the Information Store Service also resolved their issue.
After hearing this I went online to see if any others were encountering this issue. I found the below two forum posts
I then tried to reproduce this in my own environment but could not. Manually deleting the Exchange 2007 Server object from AD as well as manually deleting the Public Folder Database object did leave the 2013 Mailbox Databases pointing to the ghosted objects, but I did not receive the prompts. It appears there’s a particular chain of events that causes this issue but even though I could not recreate them in my lab, it certainly seems like people are running into the issue in the wild. If you start receiving these prompts then I suggest looking to make sure your attributes are not also pointed to ghosted objects.
Note: I was also informed that you could leave yourself in this scenario by incorrectly performing a migration from Legacy Public Folders to Modern Public Folders.
During the migration, you run the “Set-Mailbox <PublicFolderMailboxName> –PublicFolder –IsExcludedFromServingHierarchy:$True” command to prevent the Modern Public Folders from serving the Hierarchy requests while you’re moving data over; when you eventually complete the migration you should run “Set-Mailbox <PublicFolderMailboxName> –PublicFolder –IsExcludedFromServingHierarchy:$False” to allow it to serve the Hierarchy requests. If you do not run this command then you may receive the same prompts.
Additional References
Troubleshooting Exchange 
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Another awesome blog by Andrew
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Thanks for the information. I assumed the error was due to having to manually delete the Public Folder via ADSI but I would have never found that attribute.
Thanks. This was a big help. We just deleted our PF because we no longer wanted to use them going forward with Exchange 2013.
This saved me! Thank you!
Thank you, this is very helpful
thank you .it solved my proplem
Thanks you. This fixed it for me also. I was upgrading from Exchange 2010 to 2013.
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This was a great fix and one I found rather quickly. Thanks for the fix and references.
Thank you.
Thank you! I hope this is the fix!!
I did these steps and I’m still getting the pop up about every 15 mins. Any other suggestions.
Ensure AD replication has occurred, IIS has been restarted, and in the worst case scenario, you might try deleting the .ost file.
I looked at ADSI on all the DCs and that setting is removed on all of them, so i would only assume it finished replicating. I stopped and started the Information store service, but not done an iisreset yet. After the Information Store reset the error still kept coming up. I’m scheduling a reboot of the server this evening, unless you don’t think that will help.
Quality post this page and the below link is all you need for this error
https://blogs.technet.microsoft.com/vytas/2014/11/12/your-administrator-has-made-a-change-and-requires-you-to-restart-outlook/
I got this error because I forcefully removed a public folder from ADSI edit, I could not remove it cleanly.
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