Around a year ago, I was experimenting with old roblox’s place files, which would NOT open on modern roblox.
I think this test was successful. Although I need to test this more, hence the old terrain did not port through to Modern roblox.
Edit: 06/02/2021 @ 8:34PM UTC +3:00 / UTC + 2:00
I added an additional picture to what happens if you open a place file with old roblox terrain in 2021 version of studio
Looks like roblox discontinued old terrain back in 2017
The solution is to port that place to the 2017 version of Roblox Studio, then to port to the latest version of Roblox Studio
IMPORTANT: Make a copy of that place. Once you save it in the new version of Roblox Studio, YOU CANNOT REOPEN ON OLDER VERSIONS OF ROBLOX STUDIO