How to Debug PHP Scripts: Why Am I Getting Blank Screens Instead of Error Messages?

How to Obtain Informative Error Messages in PHP

When executing PHP scripts, users may encounter an issue where there is an absence of error messages, resulting in a blank screen. This hinders troubleshooting since the source of the problem remains unknown.

Modifying Configuration Directives

PHP's default configuration is to suppress error messages for security reasons, preventing customers from seeing them. However, developers can manually enable error display through the following directives:

• error_reporting: Determines which errors are reported. For comprehensive reporting, set it to E_ALL.
• display_errors: Controls whether errors are shown on the screen. Set it to 'On' to display errors.

The preferred method is adding the following code snippet to the script:

error_reporting(E_ALL);
ini_set('display_errors', 'On');

Note that on a live server, display_errors should be set back to 'Off' while error_reporting remains set to E_ALL to ensure error logging.

Error Logging

The error log file captures all PHP errors. To enable logging, set the log_errors directive to On in php.ini. This allows for thorough error analysis even if error display is disabled.

Syntax Errors

For syntax errors, the aforementioned methods may not work. Enabling them in php.ini or via .htaccess is required:

.htaccess

php_flag display_errors on
php_value error_reporting -1

php.ini

display_errors = On
error_reporting = -1

Editor Support

Using an editor with built-in error checking, such as PhpEd, VSCode, or PHPStorm, can also enhance debugging by providing detailed error information and step-by-step execution analysis.

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