I hava a mid-2012 MacBook Pro running MacOS Catalina, 10.15.7
I am a long-term Docker user and had previously been able to use Docker Desktop on this system. Some time ago Docker Desktop stopped working on the system, and I’d shifted to running Docker inside a Multipass instance, as well as running it on my Ubuntu laptop.
I want to get Docker Desktop back on this system. However, the latest download doesn’t work, because it’s compatible with macOS 11.8 (IIRC). And I saw somewhere on the Docker website that Docker Desktop is only supported for the current macOS version as well as the previous two releases.
On the Release Notes page for Docker Desktop for Mac… there are download links available for certain older releases, but at some point in the release page the download links are no longer offered.
It’s hard to determine which of the older versions might be compatible with 10.15.7. It seems that Docker Desktop 4.14 might be compatible, but there is no download link.
What I suppose this means is that Docker Inc is refusing to offer the older versions that support older unsupported macOS versions maybe because … why? I’m not sure that I understand.
I don’t have a very deep knowledge about macOS, but in general, it is hard to maintain a software on multiple versons of an operating system and it is supported on multiple operating systems as well so I guess they try to keep it as simple as possible so they can maintain it.
The reason why they delete or hide the links to odler versions could be that older Macs support older Docker Desktops which run older Docker daemon, which supports older image formats. At some point you wouldn’t be able to pull images or at least not recent versions of images. It happened without the Desktop too.
On the other hand, Rancher Desktop is supported on macOS 10.15, although you don’t get the same features, but it could be an alternative too.
There is also Podman Desktop which tries to support Docker Desktop extensions as well. I have no idea on which macOS version it is supported.
However it seems it is suppoted on macOS 11 and higher. You could still try. Maybe the version constraint is only for the current version and on older Macs it could install older Desktops.
I remember I found a GitHub repository somewhere which listed older Docker versions but I don’t remember if it was Docker CE or Docker Desktop. You could try to search for something like “Docker Desktop arhive github” or something liket hat. You could also try searching on GitHub directly.