Mojang API Rate Limit: Too Many Requests

What the log looks like

com\.mojang\.authlib\.exceptions\.AuthenticationException: The client has sent too many requests within a certain amount of time
Couldn't look up profile properties for com\.mojang\.authlib\.GameProfile@[0-9a-f]+\[.*\]\s+com\.mojang\.authlib\.exceptions\.AuthenticationException: The client has sent too many requests

How to fix it

1. Reduce the number of uncached custom player skulls placed in always-loaded spawn chunks so the server does not query Mojang for all of them at startup.
2. Check plugins that use player skins (such as Citizens, HeadDatabase, or custom tablist plugins) and enable skin caching or increase lookup delays in their configuration files.
3. If you run a Paper server behind an offline-mode BungeeCord or Velocity proxy, open your Paper configuration (paper.yml or paper-global.yml) and set bungee-online-mode (or proxy online-mode) to false so Paper stops querying Mojang for offline UUIDs.
4. If your server is on a shared hosting node where other servers share your outbound IP address, contact your host about getting a dedicated IP so other users do not exhaust your Mojang rate limit.

Check your own log