Heyo everyone!
I have got an (temporary) fix for this!
For now to fix this you will need a program like FileZilla.
You will need to download the latest buildtools from the spigot site itself.
If you have those you need to login on the root account(or an account that can access everything at the profiles) on FileZilla.
You will need to go to “/var/games/minecraft/profiles/BuildTools-latest” on the server and then delete the files in that folder (should only be the corrupt BuildTools.jar)
Then you want to upload the new file you downloaded from the spigot website to that same directory.
Now you just have to wait a bit for the web console to update.
If it has updated you should be able to just build the new 1.16.1 binaries! (or from any other version)