A diagram language is missing
A language missing from the editor picker is almost always an administrator toggle rather than a fault. Thirty-one languages is a lot for one menu, and many sites deliberately shorten the list.
TikZ is the special case: it is off by default everywhere, because rendering it runs a full TeX engine.
#What you are seeing
A language you have used before is no longer in the list.
A language you expected has never appeared.
TikZ specifically is missing.
#Work through these in order
Check | What it means and what to do |
|---|---|
Is it TikZ? | TikZ ships disabled. An administrator turns it on in the site settings. |
Has an admin shortened the list? | Site settings have a toggle per language, and presets that set the whole list at once. |
Was a preset applied? | Applying a preset replaces the whole list, including anything previously turned on by hand. |
Do existing diagrams still work? | Yes. Disabling a language never stops existing diagrams rendering or opening. |
#A few things that catch people out
Turning a language off only hides it from the picker for new diagrams.
Two admins saving language settings at the same time can overwrite each other, because the whole list is written.
The toggles and presets are documented in Administration.
#Related
Most of these take under a minute.
