i made a written book on my server i want to give it to new players i add it to a new kit but when i have the kit the book says invalid tag
What version? for both the book being created and being given to players?
Also, does the same effect occur if the book is given to players by means outside the kit? eg by hand, in a chest, via /give?
How is 'new player' defined? and does giving the book to an 'old player' work suceessfully?
There was/is a known bug in 1.14.0 involving books (and possibly other items) retaining NBT tags when enchantments were removed: this is supposed to have been fixed in one of the 1.14.1 snapshots.
Possibly a book created with the old .0 code (or a prior version like 1.13.x) might interact poorly with the newest code.
If the book can be successfully transfered outside the kit, this would suggest the issue with the tags is localized to the kit (either construction or application).
WARNING: I have an extemely "grindy" playstyle; YMMV — if this doesn't seem fun to you, mine what you can from it & bin the rest.
Its 1.13 its only in kits i wanted to give it to any new play that join my server i dont have old players