Bukkit

 Plugin Version: 3.9.2

Plugin Config:

#Do you want to turn off the automatic updates of ChestShop?
TURN_OFF_UPDATES: false

#How large should the internal caches be?
CACHE_SIZE: 1000

#(In 1/1000th of a second) How often can a player use the shop sign?
SHOP_INTERACTION_INTERVAL: 250
#Do you want to allow using shops to people in creative mode?
IGNORE_CREATIVE_MODE: true
#If true, people will buy with left-click and sell with right-click.
REVERSE_BUTTONS: false
#If true, people will be able to buy/sell in 64 stacks while holding the crouch button.
SHIFT_SELLS_IN_STACKS: false
#What can you do by clicking shift with SHIFT_SELLS_IN_STACKS turned on? (ALL/BUY/SELL)
SHIFT_ALLOWS: "ALL"
#Can shop's chest be opened by owner with right-clicking a shop's sign?
ALLOW_SIGN_CHEST_OPEN: true
#If true, when you left-click your own shop sign you won't open chest's inventory, but instead you will start destroying the sign.
ALLOW_LEFT_CLICK_DESTROYING: true

#If true, if the shop is empty, the sign is destroyed and put into the chest, so the shop isn't usable anymore.
REMOVE_EMPTY_SHOPS: false
#If true, if the REMOVE_EMPTY_SHOPS option is turned on, the chest is also destroyed.
REMOVE_EMPTY_CHESTS: false
#A list of worlds in which to remove empty shops with the previous config. Case sensitive. An empty list means all worlds.
REMOVE_EMPTY_WORLDS:
- "world1"
- "world2"

#First line of your Admin Shop's sign should look like this:
ADMIN_SHOP_NAME: "Admin Shop"
#The economy account which Admin Shops should use and to which all taxes will go
SERVER_ECONOMY_ACCOUNT: ""
#Percent of the price that should go to the server's account. (100 = 100 percent)
TAX_AMOUNT: 0
#Percent of the price that should go to the server's account when buying from an Admin Shop.
SERVER_TAX_AMOUNT: 0
#Amount of money player must pay to create a shop
SHOP_CREATION_PRICE: 10.0
#How much money do you get back when destroying a sign?
SHOP_REFUND_PRICE: 0.0

#Should we block shops that sell things for more than they buy? (This prevents newbies from creating shops that would be exploited)
BLOCK_SHOPS_WITH_SELL_PRICE_HIGHER_THAN_BUY_PRICE: true

#Do you want to allow other players to build a shop on a block where there's one already?
ALLOW_MULTIPLE_SHOPS_AT_ONE_BLOCK: false
#Can shops be used even when the buyer/seller doesn't have enough items, space or money? (The price will be scaled adequately to the item amount)
ALLOW_PARTIAL_TRANSACTIONS: true
#Can '?' be put in place of item name in order for the sign to be auto-filled?
ALLOW_AUTO_ITEM_FILL: true

#Do you want to show "Out of stock" messages?
SHOW_MESSAGE_OUT_OF_STOCK: true
#Do you want to show "Full shop" messages?
SHOW_MESSAGE_FULL_SHOP: true

#Can players hide the "Out of stock" messages with /cstoggle?
CSTOGGLE_TOGGLES_OUT_OF_STOCK: false
#Can players hide the "Full shop" messages with /cstoggle?
CSTOGGLE_TOGGLES_FULL_SHOP: false
#Do you want to show "You bought/sold... " messages?
SHOW_TRANSACTION_INFORMATION_CLIENT: true
#Do you want to show "Somebody bought/sold... " messages?
SHOW_TRANSACTION_INFORMATION_OWNER: true

#If true, plugin will log transactions in its own file
LOG_TO_FILE: false
#Do you want ChestShop's messages to show up in console?
LOG_TO_CONSOLE: true

#Do you want to stack all items up to 64 item stacks?
STACK_TO_64: false
#Do you want to use built-in protection against chest destruction?
USE_BUILT_IN_PROTECTION: true
#Do you want to have shop signs "stick" to chests?
STICK_SIGNS_TO_CHESTS: false
#EXPERIMENTAL: Do you want to turn off the default protection when another plugin is protecting the block? (Will leave the chest visually open - CraftBukkit bug!)
TURN_OFF_DEFAULT_PROTECTION_WHEN_PROTECTED_EXTERNALLY: false
#Do you want to turn off the default sign protection? Warning! Other players will be able to destroy other people's shops!
TURN_OFF_SIGN_PROTECTION: false
#Do you want to disable the hopper protection, which prevents the hoppers from taking items out of chests?
TURN_OFF_HOPPER_PROTECTION: false
#Do you want to protect shop chests with LWC?
PROTECT_CHEST_WITH_LWC: false
#Do you want to protect shop signs with LWC?
PROTECT_SIGN_WITH_LWC: false
#Should the chest's LWC protection be removed once the shop sign is destroyed?
REMOVE_LWC_PROTECTION_AUTOMATICALLY: true

#Do you want to only let people build inside regions?
WORLDGUARD_INTEGRATION: false
#Do you want to only let people build inside region flagged by doing /region regionName flag allow-shop allow?
WORLDGUARD_USE_FLAG: false
#Do you want ChestShop to respect WorldGuard's chest protection?
WORLDGUARD_USE_PROTECTION: false

#Do you want to deny shop access to unlogged users?
AUTHME_HOOK: true
#Do you want to allow shop access to unregistered users? (Example: registration is optional)
AUTHME_ALLOW_UNREGISTERED: false

#How much Heroes exp should people get for creating a ChestShop?
HEROES_EXP: 100.0

#Add icons and make item names hoverable in transaction messages when ShowItem is installed?
SHOWITEM_MESSAGE: true

Server Version: git-Paper-244 (MC: 1.15.2)

What other plugins are you running?

-ChestShop

-Essentials (Normal, Chat and Spawn)

-GreifPrevention

-KillerMoney

-LockettePro

-mcMMO

-PermissionEX

-PlayerServer

-Ultimate_Vote

-Vault

What is happening?

I am trying to write a sign that let's me sell enchanted books, in my exact scenario mending books I bought from a villager. However it keeps saying that "You have specificed invalid item id!". I have tried many different names and number IDs for the mending book, including 403:2 403#2 and EnchantedBook#2, etc. with no luck. Does anybody have any ideas of how to fix this?

What did you expect to happen?

I was hoping that I would be able to type the code for the enchanted book on the sign and have the books be sold easily from the chest.

Please provide any additional info below

I have tried selling the books just as Enchanted_Book but this also does not work unfortuantely. Any ideas would be greatly appreciated.

You are not running the latest version of the plugin, your old version is not compatible with anything beyond 1.13. Please update and see if the issue persists.