DestinationMapping Report, Script, and Upload

Updating my post with my own findings from trial and error.

Oh, hey, the documentation changed. Previously it said "If your SharePoint has more than 50-K sites, Microsoft 365 group autodestination mapping may not work perfectly." That number has changed to 100-K sites as of 9/25/2023.

After getting the Destination Mapping template downloaded, the Microsoft Documentation seems to suggest that you have to run StreamClassicVideoReportGenerator_V1.11.ps1 with some parameters to create a new file with destination paths filled in. As near as I can tell, the only purpose of this step is for mapping M365Group containers that show up as NULL in the MigrationDestinations.csv. It will proceed to "automap" those NULL values to the respective SharePoint sites for those M365 Groups. I don't think it's going to help you in cases where the M365 Group has already been deleted, the M365 Group exists but has no SharePoint site, or where you want to map any container to a site different from the site suggested by the Migration tool. But as I said, I wasn't able to get the script to work, so I'm kind of guessing about what it's supposed to do.

From there, I tried doing some manual filling in of Destination Paths to the CSV file for some M365 Group Containers and Companywide Channel containers. Generally it seemed to work well. It did not like one site that had double quotations in the container's name.

It does seem to me that this whole process is a bit limited by the fact that you have to move your containers to the Migrations tab just in order to be able to set destinations. I was hoping to set all my destinations now and migrate in waves later. I guess I can still do that, but I was hoping to only move things to the Migrations tab when I was actually ready to migrate them.

If you really need help with mapping your M365 Groups, I'd suggest you or someone who is an Exchange admin run the Get-UnifiedGroup command so you can find the appropriate group by PrimarySMTPAddress (as indicated in the Stream Inventory Report on the "ContainerEmailId" column) and locate its SharePointSiteURL to put into the MigrationDestinations.csv for the Destination Path column. Here's a sample of the command.

Get-UnifiedGroup -Resultsize Unlimited | Select Name, DisplayName, PrimarySmtpAddress, SharePointSiteUrl | Export-CSV AllUnifiedGroups.csv -NoTypeInformation
(other properties you might find helpful: Guid, GroupMemberCount, WhenCreatedUTC, ManagedBy)

Tip: if you haven't tried the "tagging" function of the SharePoint Stream Migration Tool yet, it works really well! It gives a nice visual on the tags and helps be able to filter your containers whether you're working from the Scans tab or the Migrations tab.

https://learn.microsoft.com/en-us/stream/streamnew/understand-the-tool#tags
https://learn.microsoft.com/en-us/sharepointmigration/mm-tagging

Tip: In my work with the Stream Migration, I've now run into issues with one Container that had a Pipe symbol in its name, and another with double quotes in its name. So if you're just getting started on all this, you might want to review all your Container names for things like that and consider changing them to eliminate headaches later, or be prepared to carefully scrutinize any import or export files you may use.

Here's my summary rewrite on how to work with the Destination Mapping.

To Download the Destination Mapping Template:
-Launch the Stream Migration Tool from Admin Center (Admin Center > Setup > Migrations > Mirosoft Stream)
-Select some containers you want to work with and scan them
-Once Scans are complete for each container, select them again and "Add to Migrations"
-Click the Migrations tab
-Once on the Migrations tab, click the "Upload Destinations" button
-On the popup\dialog box for Destination uploading, there's a link for "MigrationDestinations (.CSV)"
-Click that link, to download a CSV file that will list only the containers you've loaded into the Migrations Tab
-That MigrationDestinations.csv file has the following headers: Name (for reference only), Source Path (for reference only), Destination Path, Migration status (for reference only), Created on (for reference only), Task ID

To edit the Destination Mapping File
-Open in Excel or text editor and make changes to the Destination Path column only.

To upload a Destination Mapping File after editing:  
-From the Migrations tab, click the "Upload Destinations" button
-On the popup\dialog box for Destination uploading, Specify the CSV file containing the altered Destination Paths