Heck it isn’t even listed in archives or here when I am suppose to select the version ( so I picked 5.0). This is a complete disaster and I have tried EVERYTHING I could think of to get past the license server screen. Always a popup saying peer certificate cannot be authenticated. Why does a free version even require this? I started a project in 3.x and over the years upgraded gradually until I hit version 5 and broke the game completely so I reverted back to 4.7.2. 12 years and thousands of hours of work is now, seemingly toast. Nothing but crickets from support and that will likely be the case here , too. Hell I’ll BUY the damn thing for ANY amount they want to charge me as I can’t even put a price on the anguish of losing everything
First I suggest that you get your project under proper source control. This is just Economics 101: if your project has value to you, protect that value.
Unity has one of the lowest-friction upgrade paths in the world. I have games that I started in Unity 3.5 that I have kept current and build in Unity2020 today.
But it does require diligence on your part. The more versions you step past, the more things will break and require fixing.
Second, get a more-recent LTS version of Unity going and start bringing in portions of your project. Since you have waited through so many versions there will likely be more things that need attention and twiddling.
If there is any Javascript / UnityScript in your project, all of those files will not work and will need to be upgraded or removed.
I replaced all javascript files years ago - which was an undertaking in itself as that was the popular scripting when I started this ages ago. I have the project saved in several places/drives so as not to ever outright lose it. The problem is just in the upgrading from 4.7.2. I tried to do it incrementally, but 5.0 required a license whereas what I am using now, 5.6.7, did not. Perhaps some versions in between there that I could have installed first without a license for a free version. Mostly things are playable now at least but buggy. The standard asset car, for instance, I converted to a boat and ran beautifully in 4.7.2 but not anymore. Had to change the wheel mass from 1 to anything from 10 to 50 while tweaking rigidbody perameters of the car to try to get back that feeling of being in a boat and not a car. I could not throw grenades ( they would just instantiate and hang) but I could throw molatov cocktails just fine ( odd because all scripts exactly the same - fixed by just placing a grenade model in the cocktail replacing the bottle and it worked) . My FPS player runs fine in one scene but does not move in another scene. Again the exact same scripts. I am hoping that when my computer gets back from repairs that it can run 4.7.2 as it did before the power supply destroyed by the hurricane Helene which would make the problem opening 4.7.2 a new computer/install issue. I never had that “connecting to license server” screen pop up before. EVER. So there is hope…but going back through a project that I had been working on for about 12 years and fixing stuff .