Contributed by
Javier Eguiluz
in #20951.

Symfony exception pages provide detailed information, such as logs and stack traces, about the errors that happen during the execution of your applications. They are immensely useful, but their design was a bit outdated, specially since we redesigned the toolbar and the profiler in Symfony 2.8.

In Symfony 3.3 we decided to redesign the exception pages to keep displaying all the information that you need but with a fresh coat of paint. The new design is based on a big red header with the actionable error message. The rest of the contents (stack traces, logs, etc.) are displayed on tabs:

This is a better comparison between the existing and the new design:

The new design is highly dynamic, with toggles everywhere, and little features such as a new favicon to better spot error pages on your browser, a smart code snippet expanding that always tries to expand your own code first instead of Symfony or other vendors code, etc.

This redesign was also the perfect excuse to update our cute exception ghost. In this new design he/she is even happier about your exceptions: