"Restricted name, cannot use ... as a plugin name"

Server log

org.bukkit.plugin.InvalidDescriptionException: Restricted name, cannot use minecraft as a plugin name.

What it means

A few plugin names are reserved by the server and the plugin is not loaded.

What causes it

The plugin is named bukkit, minecraft, mojang, spigot or paper. Upper or lower case does not matter.

How to fix it

Before

name: Paper

After

name: PaperTweaks

Check the whole file. Paste your plugin.yml or drop the plugin jar into Permistry. It finds this and about 40 other problems, and explains each one in plain words. It runs in your browser and nothing is uploaded.

Open the checker