Attempting to cast a great spell from an ancient scroll (or with the scroll's pattern) causes a strange error instead of attempting to cast.

Whoops, closed when I closed #309

Whoops. Try running /hexcasting recalcPatterns first and see if that helps.

Incidentally, is this a new world? And are you on Forge or Fabric? (I ask because some people on the discord are having the same problem.)

Update. After a suggestion, running /hexcasting recalcPatterns allowed the spell to be cast.
This command requires OP to run.
Ideally, this shouldn't be necessary...
New world, forge, added Hex Casting to Enigmatica 9.