Bug unity does not find reference to NetworkBehaviour

More than a bug it is a design error of unity.


In 2017 I had created a multiplayer project that worked quite well. Only it used (probably) NetworkBehaviour, or at least NetworkBehaviour is the class that my scripts inherit from. At the time, the version of unity I sated was still using the old numbering.
Having ascertained that NONE of the modern networking systems work for me, and that even opening the project with 5.6.7f1 does not open it at all and freezes without giving any error, how do I do it?
I cannot redo the project from the beginning, especially since NetworkBehaviour in 2017 worked, all modern methods do not!

 

Are you aware that the NetworkBehaviour from 2017 (UNET?) cannot be compared to today's NetworkBehaviour which must be from Netcode. Those are two different tech stacks.

Other than that, I hope you tried to open throw-away copies of your project in all the various editor versions. If not, you could have corrupted your project.

 

Aware?
I can assume that it was better on paper, whether it really is, considering that I can't make it work, I dare to doubt.
Different? I don't doubt it.

But wouldn't it have been easier to keep the old interface by changing the backend behavior?
So you force poor developers to learn new methods every few years, which doing it as a hobby becomes untenable, especially when the previous method worked and I can't find a tutorial I can follow of the new one.
To make matters worse, I would like to lament how, according to what I have read, when I was starting a new multiplayer project a few months ago, Multiplayer HLAPI was still in place, but it was decommissioned before the official launch of Netcode.


I tried running the backup project from the last time it worked, that was the result.