I am unsure if this is just a GCC High bug, but if you navigate to your SharePoint online admin portal and click on the migration link on the left side, you get an endless spinning icon.
My first thought was to check the dev tools to see if it was some how getting blocked, but all it showed was a status code of 200 doing a POST. Off to the AAD Sign-in Logs…
After filtering for my account, I saw a generic app is disabled message.
It didn’t dawn on me, but a co worker did see that the app was disabled in Enterprise Applications and under Microsoft applications. Thinking that was it, but nope, next error:
At this point, my gut was telling me something is wrong on Microsoft’s end. I popped a ticket and once they circled back to the SharePoint team, it is indeed a bug. So, how do you workaround this? Add /fileshare to the end of the URL.
After that, the Migration manager pulled up…
Azure Testing Site 