Roblox studio throws http 500 internal server error when saving

if it keeps happening on one place while your other places save fine, it might be the place itself. try publishing a copy with a chunk of the heavy stuff deleted. if that goes through, it's size, not an outage.

500 is almost always Roblox's end, not your place. Do File > Save to File so you have a local .rbxl copy and nothing gets lost, then try publishing again in a bit. Check whether anyone else is reporting an outage before you start pulling your game apart.