How can one troubleshoot and resolve the session_start error in PHP?

The "session_start" error in PHP usually occurs when the session has already been started elsewhere in the code before calling session_start again. To resolve this issue, you can check if the session has already been started using session_status() function and only call session_start if the session is not active.

if (session_status() == PHP_SESSION_NONE) {
    session_start();
}