How do I stop this from happening?

at the risk of sounding cliché, try logging off, and logging back in again.

And with no disrespect to your intelligence, you may have typed /sethome wrong, it happens to me now and again.

Also, the /home command is blocked in certain areas, most notably the spawn. try warping away then doing /home.

Hope I helped.

I think it could be a temporary server problem. Many other things in the server these days have not been completely functional due to recent updates, so Im hoping it'll be resolved soon.

There is (if it is still there) a cooldown on home and many other commands. the /home command has a 30 CD so just be patient

It's true that some areas have /home disable but if the screenshot is a proper representation of the problem, the issue is a client-side chunk error. The solution is to relog or if you know of the some nearby warps, test going to them and back. Once you force your client to download the "missing" chunk, it'll be fine.

thanks everyone

I have the same problem as you sometimes, I /home then I just fall through the map and I am forced to log in and out to fix it.