Disclosure: I'm the developer of Mermaid Editor for Confluence, mentioned at the end. The checks below work for any app.
You export a Confluence page to PDF for an audit, a customer or a printed handbook, and the diagram is gone. A blank space, or a line like "Error loading the extension!". The page itself looked fine.
WHY IT HAPPENS
Many diagram apps for Confluence Cloud draw the diagram in your browser, inside a small frame. That works on screen. A PDF or Word export is made by Confluence on the server, where there is no browser to draw in. The app has to give Confluence something to put in the export instead, like a picture or the diagram's text. Apps built on Forge do that with a separate export function. If an app doesn't have one, the export has nothing to show.
HOW TO CHECK, IN TWO MINUTES
1. Make a test page with one diagram from each app you use.
2. Export it: ··· > Export > PDF. Then also Word.
3. Look at what each diagram became: a picture, its source code, a blank space or an error.
Do this before an export really matters, and again after you add a new app.
IF A DIAGRAM IS MISSING
- Ask the vendor whether PDF export is supported. It's a fair question; some apps added it later.
- Workaround for one important document: export the diagram as an image from the app (most diagram apps can), put the image on a copy of the page, and export that copy.
WHAT MERMAID EDITOR FOR CONFLUENCE DOES
Since the November 2026 release (Marketplace version 3.10.0) a PDF export shows each Mermaid diagram as a picture. The picture is made when you insert the diagram, and kept in the app's storage in your own Atlassian site. Word export shows the Mermaid code with a short note. Diagrams inserted before that release get their picture the next time you open them in the editor and click Insert diagram. It's free on the Marketplace: https://marketplace.atlassian.com/apps/4235692896
Happy to answer questions about diagrams in Confluence exports, whichever app you use.
