Yep, as it says, your Spine installation is out of date and you'll need to download and reinstall Spine.
We made some great improvements to the Spine launcher. That is the part that not only shows the launcher window and starts the Spine editor, but is also the foundation that the Spine editor runs on top of. The improvements make Spine a lot faster, both start up and the editor itself. In some cases it's more than 20% faster! Unfortunately the improvements mean that editor versions 4.0.55-beta and later require reinstalling Spine.
We have a nicer dialog that explains it better and links to this page:
Spine: Reinstallation
However, this was the first time we needed that dialog and it had a bug, so we couldn't use the dialog this time. It'll work next time, if we ever need it again! We try not to require launcher reinstallation, but sometimes it can't be avoided.
