Hello. I am getting this message on a homebrew warlock I am working on. I know this tends to come up with spells that are not part of the Basic Rules or SRD. But the spells I am using are Animal Friendship, Feather Fall, Animal Messenger, Web, Conjure Animals, Bestow Curse, Giant Insect, Polymorph, Awaken and Cloudkill. As far as I am aware, all of these spells are in the basic rules/SRD. Is there another issue or is one of the above spells causing the problem?

Click the Orange Save Button.

Well, either you are missing something (check everything, not just spells) or raise support ticket using contact us link below.

Might help if you can link to homebrew so mods can take a look and see what you might have not (doesn't need to be published).