Discord error 30030: Maximum number of server categories reached (5)

This one is easy to misread. "Server categories" here refers to Discord's discovery/server-directory categories (the tags a public server selects to describe itself), not channel categories. A guild can select at most five. The error appears when a bot, or a user acting through OAuth2, tries to update the guild's discovery metadata with more than five categories.

If you arrived here expecting channel categories: channel categories (channel type 4) are limited differently and creating too many of them produces 30013 (500 channels total), not 30030. Very few bots touch discovery metadata, so if you see 30030 from a general-purpose bot, check which endpoint you are calling.

{
  "message": "Maximum number of server categories has been reached (5)",
  "code": 30030
}

Validate discovery category lists client-side (length 5 or fewer) before sending. Keep an eye on the literal message string in your logs rather than assuming what a 30xxx code means from its number.

When building discovery or server-settings features, fetch the current values first and present them to the admin before writing, so the five-category ceiling is visible in the UI. If you support both discovery categories and channel categories in one bot, name the two concepts differently in code and logs to avoid confusing the two errors when they occur.

The lesson generalizes: 30xxx codes name a numeric cap, and the literal message names the resource, so log messages, not just codes. The per-guild caps that bots actually hit day-to-day are tabulated on the Discord limits page.