Catch All Errors & Exceptions In PHP (Simple Examples)

Welcome to a quick tutorial on how to catch all errors and exceptions in PHP. Need to cast a net and capture all the errors to figure out what went wrong?

That covers the quick basics, but read on if you need detailed examples.

 

 

TABLE OF CONTENTS

 

 

EXAMPLE CODE DOWNLOAD

Source code on GitHub Gist

Just click on “download zip” or do a git clone. I have released it under the MIT license, so feel free to build on top of it or use it in your own project.

 

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1) BASIC PHP ERROR HANDLING

<?php
// (A) ERROR REPORTING LEVEL
// E_ALL, E_WARNING, E_STRICT, E_PARSE, E_DEPRECATED, E_NOTICE
error_reporting(E_ALL);
 
// (B) SAVE TO ERROR LOG FILE
ini_set("log_errors", 1);
ini_set("error_log", __DIR__ . DIRECTORY_SEPARATOR . "error.log");
 
// (C) DISPLAY ERROR MESSAGES?
// NOTE: WILL SHOW "GENERIC" 500 ERROR IF TURNED OFF & NO SET_EXCEPTION_HANDLER()
// NOTE: IF ERROR_REPORTING(0), THIS WILL NOT SHOW ANYTHING.
ini_set("display_errors", 1);
 
// (D) THROW EXCEPTION
throw new Exception("TEST ERROR!");

Before we get into “catch errors”, here is a quick crash course on the default PHP error handling mechanisms. Yes, this is important. Some people skipped the basics, and wonder why “errors are not showing” when error reporting is turned off…

1. Use error_reporting() to control what kinds of errors need to be reported – From everything E_ALL, to warnings E_WARNING, to boring notices E_NOTICE. I will leave a link to the full list below.
2. log_errors and error_log to define if errors should be saved to a log file.
3. Lastly, use display_errors to control if errors should be displayed on the screen during runtime.
   • Not to be confused – We can turn off display_errors, but keep errors in a log file.
   • But when error_reporting() is set to “don’t report any errors”, PHP will not show any errors nor save them into the log file.

P.S. All of these can be set in php.ini.

 

 

2) DISPLAYING A CUSTOM ERROR SCREEN

<?php
// (A) ERROR HANDLING SETTINGS
error_reporting(E_ALL & ~E_NOTICE);
ini_set("display_errors", 0);
ini_set("log_errors", 1);
ini_set("error_log", __DIR__ . DIRECTORY_SEPARATOR . "error.log");
 
// (B) CATCH ALL ERRORS
set_exception_handler(function($ex) {
  // (B1) DO YOUR OWN ERROR HANDLING IF YOU WANT
  // print_r($ex);
  // error_log("YOUR EXTRA MESSAGE OR DATA");
 
  // (B2) SHOW CUSTOM ERROR MESSAGE ?>
  <div style="position:fixed; top:0; left:0; z-index:99999;
       width:100vw; height:100vw; padding:10px; background:#fff">
    <h1>HAIYAA, AN ERROR HAS OCCURED.</h1>
    <p>The developers have been shamed and disowned from the family.</p>
  </div>
<?php });
 
// (C) THROW EXCEPTION
throw new Exception("TEST ERROR!");
echo "This will not run";

As in the introduction above, we use the set_exception_handler() function to capture all the errors and exceptions. In what situation should we do this? If you need to do a “graceful crash”.

• Save some data, so the user doesn’t lose everything. Or maybe even a possible “recovery” option.
• Show your custom error message.

 

 

3) SAVE ERRORS TO THE DATABASE

3A) ERROR DATABASE TABLE

CREATE TABLE `errors` (
  `date` datetime NOT NULL DEFAULT current_timestamp(),
  `file` varchar(255) NOT NULL,
  `line` varchar(255) NOT NULL,
  `message` text NOT NULL,
  `trace` text NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
 
ALTER TABLE `errors`
  ADD KEY `date` (`date`);

If you want to save the error into the database, here’s a quick dummy table you can work on.

 

3B) ERROR TO DATABASE

<?php
// (A) DATABASE SETTINGS - CHANGE TO YOUR OWN!
define("DB_HOST", "localhost");
define("DB_NAME", "test");
define("DB_CHARSET", "utf8");
define("DB_USER", "root");
define("DB_PASSWORD", "");
 
// (B) ERROR HANDLING SETTINGS
error_reporting(E_ALL & ~E_NOTICE);
ini_set("display_errors", 0); 
ini_set("log_errors", 0);
 
// (C) ERROR HANDLER
set_exception_handler(function($ex) {
  // (C1) CONNECT TO DATABASE
  $pdo = new PDO(
    "mysql:host=". DB_HOST .";charset=". DB_CHARSET .";dbname=". DB_NAME,
    DB_USER, DB_PASSWORD, [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
  ]);
 
  // (C2) SAVE ERROR TO DATABASE
  $stmt = $pdo->prepare("INSERT INTO `errors` (`file`, `line`, `message`, `trace`) VALUES (?,?,?,?)");
  $stmt->execute([
    $ex->getFile(), $ex->getLine(),
    $ex->getMessage(), $ex->getTraceAsString()
  ]);
 
  // (C3) THEN SHOW YOUR CUSTOM ERROR MESSAGE
  echo "Mr. Stark, I don't feel so good.";
});
 
// (D) THROW EXCEPTION
throw new Exception("TEST ERROR!");
echo "This will not run";

This should be pretty self-explanatory – We save any errors into the database instead.

 

 

 

LINKS & REFERENCES

• Error Log – PHP
• Error Reporting Constants – PHP
• Set Error Handler – PHP