Error Solved: Public Folder Export property expression isn’t valid

Your company is in the process of migrating from Microsoft Exchange Server 2010 or its predecessors to Exchange 2013. After checking that Exchange 2010 can co-exist with Exchange 2013 you go ahead and setup the server, create the mailbox database, setup the certificates, Outlook Anywhere, network routes and changes into the firewall. You start by moving all the mailboxes from one server to another and all is working fine. All mailboxes have been migrated and the only remaining thing is the Public Folders which is heavily used by the users.

To migrate a public folder from Exchange 2010 to Exchange 2013 there is a whole process to go through which steps can be found on the Official Microsoft article. We will not be going through the process as it’s a lengthy one but we will go through a common issue that most users face on their migration processes, such as Public Folder Export property expression isn’t valid. You can follow the steps below to troubleshoot and fix the problem. You may also use an EDB to PST converter tool, such as Stellar Converter for EDB to export Public Folders from Exchange to PST format or Live Exchange and Office 365 account in a few clicks.

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Steps to Resolve Public Folder Export property expression isn’t valid Issue

So, after starting off with the migration process you create the export request for the public folder as below from the Exchange 2010 Server.

New-PublicFolderMigrationRequest –SourceDatabsase (Get-PublicFolderDatabase –Server ex01) –CSVData (Get-Content FolderMigration.csv –Encoding Byte)

This will create the request to move the public folders stated in the CSV file provided from the steps of the migration plan. Once the process start you can see the progress by using the command below.

Get-PublicFolderMigrationRequest | Get-PublicFolderMigrationRequestStatistics 

This will give you a picture of the status and if there are any issues. We will be looking at the failures that could happen in particular this one.

When you run the command below you will notice the PercentComplete at 10% and the StatusDetail showing FailedOther. Now, this isn’t much helpful but if we want more details on the matter we can run the command below.

Get-PublicFolderMirgrationRequest |Get-PublicFolderMigrationRequestStatistics | FL

This will give us more insight on the issue at hand. You will notice the error below saying “Error: Property expression isn’t valid.

Public Folder Export property expression isn't valid

From Exchange 2013 updwards some characters from previous versions of Exchange have been deemed invalid or illegal characters. The next step here onwards is to go to the public folder and fix all the email enabled public folders which have invalid aliases. The best thing is to literally make the name only characters of the alphabet and numbers, keeping in mind that no spaces are to be made. If you have more than one you can run the following command to get the list of folders which have spaces in them. This will only show the ones having spaces, to search for other specific character from the invalid list from the screenshot above you would need to change the Where-Object part.

Get-MailPublicFolder | Where-Object {$_.Alias -like "* *"} | Select-Object alias, identity

Now that we have identified the issue and which public folders have the problem we can have two options to fix the problem.

Option 1 – Exchange Management Console

Open the Exchange Management Console from the Exchange 2010, once it loaded open the Public Folder Management console from Tools. Expand the Public folder tree and open the properties of your public folder which is listed to have a space or any of the illegal character. Click on the Exchange General tab and change the alias as show in the screenshot below

Public Folder Export property expression isn't valid

Option 2 – Exchange Management Shell

Open the Exchange Management Shell on the Exchange 2010 and type the following command

Get-MailPublicFolder “Comp Contracts” | Set-MailPublicFolder –Alias “CompContracts”

Of course if you have one public folder this should be an easy task, but if you have a good number of public folders, it could require to setup some kind of script to go through the public folders and remove the spaces which could take some time especially if some folders have illegal characters and others have spaces. Either that or you go through the UI one by one which could take a lot of time.

Once you sorted out the naming conventions of the aliases it is suggested to remove the public folder request. This can be done by firstly see the requests using the Get-PublicFolderMigrationRequest and then running the Get-PublicFolderMigrationRequest | Remove-PublicFolderMigrationRequest. This will remove all requests. You can execute again the command to create the public folder migration batch.

There are other factors to keep in mind as when re-running the migration batch you could encounter other issues which could delay or even show-stop the whole migration process. In these cases it would be recommended to use third party applications such as Stellar Converter for EDB which can export anything from your EDB files from any Exchange version including Public Folders and export them to PST and other formats. EDB to PST Converter Software can also export the public folders directly to Office 365 or to a live Exchange server minimizing the administrative effort and headaches. You can free download now(100% Secure) and Preview your Converted PST file free!!

  1. Rene Dwis February 18, 2020
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