Well, since at home I have CS2 and at uni they have CS, I have encountered this problem. First time i tried to open a CS2 file, it told me I had to update. So I did, and it worked. This was on a Mac if I remember correctly.
But when I tried this on another PC, i had to manually install the update, and it still didn´t work.. I have no idea why.
Watercooled 5950X | AORUS Master X570 | Asus RTX 3090 TUF Gaming OC | 64Gb RAM | 1Tb 970 Evo Plus + 2Tb 660p | etc etc