Error Pages

When a page fails while you develop (server.debug: true), the error page shows where: the .q file, the lines around the one that failed with that line marked, the message — which says what to change — and links to the SPEC rules the message cites (PARSE-2, ACT-9…). The Python traceback is there too, folded, for when the problem is in Quantum itself.

The line is the innermost one that failed:

• a parse error points at the tag (<q:sett> on line 3);
• a runtime error points at the statement — the q:set inside the q:if, not the q:if;
• an error inside a component you called points into that component's file, not at the <Card /> that called it.

Parse errors carry the line everywhere, not only on the page: quantum run and the logs print at line 3: <q:sett name="x" value="1"/>.

With debug: false the page says only that an error happened — no source, no message details. Everything on an error page is escaped: a message can carry what the request sent.

Reloading keeps you logged in

With debug: true and reload: true, saving a file restarts the server process. Without a configured security.secret_key, each process used to invent its own session key, so every save logged everyone out. In debug mode the key is now kept in .quantum/dev-secret-key next to your quantum.config.yaml (git-ignore .quantum/), and sessions survive reloads. In production, set QUANTUM_SECRET_KEY or security.secret_key — the file is never used with debug: false.