You can find the up to date information on this page:

There have been so many updates and everyone is in different stages of migration so it’s been a nightmare to consolidate information. It’s best to browse from the world-building section to find what you need.

Note: These instructions only apply for Unity Versions 2020.3.9 and onwards. This article was written in anticipation of future updates after 3rd June 2021 announcements.

Update Unity AltSpace Uploader via MRFT Tool (New Way)

So before this update you had to delete folders in your project to be able to then bring in the new version of the AltSpace Unity uploader package.

This was tricky and unsafe to do so for most people but the new way which is current as of version 2020.3.9 you can update directly using the MRFT.

I made the mistake of selecting 0.9.1 so I had to open up this tool and go back to my project and update it. After verifying the update worked I was then able to upload my world as there has been an update since launch.

The steps are very much identical but you may want to validate your files just to make sure there are no problems.

I like the toolkit!

It was super easy to update my Unity world uploader without having to be overcautious which was a nice change of pace.