During the Q&A portion of the 09/17/2021 John Mueller hangout, one webmaster asked John about the context of a site migration and Google’s change of address tool.
The webmaster explained they did everything according to all migration requirements and recommendations. They updated redirects, canonical tags, and tested things before they fully launched the new migration. And, of course, they added the new property—they did everything.
However, they were unable to get the change of address to work. There was a validation error, a 301 redirect where it couldn’t fetch the old domain.
The webmaster wondered how they can pass validation for this tool, especially since they did everything they were supposed to.
John explained that this tool is simply a signal that Google uses with respect to migrations. This tool is not a requirement.
If you can’t get the change of address to work and you have everything set up properly, you’ve done all you can do.
You don’t absolutely have to implement the change of address tool as part of your migration.
This conversation occurs at approximately the 20:39 mark in the video.