# Fenced diagram block renders as plain code instead of a picture

**What you are seeing**

A fenced diagram block renders as plain code instead of a picture.

---

## Why it happens

Either the language is not one of the 27 supported diagram languages, or no signed-in session token was available, in which case the block is left as-is with no error.

---

## What to do

Check the language name against the supported list, and reload the page so the session token is issued. Diagrams do not render for logged-out viewers.

---

## Settings involved

| **Setting**             | **Where** | **What it does** |
| ----------------------- | --------- | ---------------- |
| Administration settings | Nowhere   | \-               |

---

## Limits that apply here

| **Limit**              | **Value**    | **What happens**                                                                                                                                                                                         |
| ---------------------- | ------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Diagram languages      | 27 languages | Only blockdiag, bpmn, bytefield, seqdiag, actdiag, nwdiag, packetdiag, rackdiag, c4plantuml, d2, dbml, ditaa, erd, excalidraw, graphviz, mermaid, nomnoml, pikchr, plantuml, structurizr, svgbob, umlet, |
| Session token lifetime | 20 minutes   | The short-lived token that authorises diagram rendering and image proxying lasts 20 minutes and is refreshed after 18 minutes, on window focus and on reconnect.                                         |

---

## A few things that catch people out

* There is no admin or project-level configuration at all: no access restrictions, no diagram-language toggles, no self-hosted renderer setting, no approved-domain management.
* Permission enforcement is app-managed, so newly requested permissions ship to all installs immediately and sit pending admin approval rather than blocking the install.

---

## Related

[Someone else changed the tab order for everyone on an issueThe sort preference is stored on the issue, not on the user, so it is shared by all viewer](https://help.gocapable.com/jira-markdown/someone-else-changed-the-tab-order-for-everyone-on-an-issue.html)

[Getting started view keeps coming backThe dismissal is stored in browser localStorage, not on the server.](https://help.gocapable.com/jira-markdown/getting-started-view-keeps-coming-back.html)

[Everything elseThe rest of this family.](https://help.gocapable.com/jira-markdown/everything-else.html)

---

_Found it? Good._