Do you know which plugin has this issue? If you don't, try putting the cracked plugins one at the time in the plugins folder and start the server each time until the error pops up.
Name of resource requested: Shop - a simple, intuitive shop plugin
Link to resource: https://www.spigotmc.org/resources/shop-a-simple-intuitive-shop-plugin.9628/
Price: 7.50 USD
Version: 1.7.3
Nice plugin, latest update would be cool
1 - ) Adding a Skript section, so that premium and free skripts can be in a separate section instead of being with the plugins.
Pros : Having a differenciated section for skripts helps people that download leaks expecting it to be a plugin and then they find out it's a skript.
Cons : Will not...