As of now there isHow to Optimize your Development Environment for Debugging as a cookbook entry for debugging. But what do you think of pushing that a bit further? For example we could talk about:

• TheVarDumper component: I wouldn't expect a lengthy explanation on it, but at least mentioning it, showing an example and providing a link to the doc
• How to debug step by step with XDebug: maybe a bit more tricky as can depend of the IDE. So not sure of how to push that but but maybe mentioning it would be enough with links as to how to set it up.
• Useful Symfony commands helpful for debugging: how to list all the routes, the container services, parameters...
• A word ofREPL withPsySH and its Symfony integrationPsyshBundle

In short, without pretending to cover everything about debugging, I would find it nice to have an entry listing some tools available for debugging.