How to solve the “Cannot modify header information – headers already sent by…” error in your PHP applications

Today, when I updated a repository in git I realized that my co-workers -accidentally- broke a project (in CakePHP). What error was displaying? simple and a little confusing: Warning (2): Cannot modify header information – headers already sent by (output started at /app/config/database.php:1) [CORE/cake/libs/controller/controller.php, line 742] So, for solving this common PHP issue, I recommend…