Magento 2 how to print debug trace to check any error details

To print debug traces in Magento 2 for checking error details, you can follow these steps:

1. Enable Developer Mode: Ensure that your Magento 2 installation is in developer mode. Developer mode provides more detailed error messages and is easier to debug.

   bin/magento deploy:mode:set developer

2. Enable Logging: Magento 2 uses Monolog for logging. Ensure that logging is enabled in your app/etc/env.php file by setting 'log' => ['level' => 'debug'].
3. Using the Logger: You can use Magento’s built-in logging functionality to log messages to var/log/system.log or create a custom log file.
   • Log to system.log:
     

     <?php
     namespace Vendor\Module\Controller\Index;
     
     use Psr\Log\LoggerInterface;
     
     class Index extends \Magento\Framework\App\Action\Action
     {
         protected $logger;
     
         public function __construct(
             \Magento\Framework\App\Action\Context $context,
             LoggerInterface $logger
         ) {
             $this->logger = $logger;
             parent::__construct($context);
         }
     
         public function execute()
         {
             $this->logger->debug('Debug message');
             $this->logger->debug(print_r($someVariable, true)); // For printing array or object
             // Your code here
         }
     }

   • Log to a custom file:

     <?php
     namespace Vendor\Module\Controller\Index;
     
     use Magento\Framework\Logger\Monolog;
     
     class Index extends \Magento\Framework\App\Action\Action
     {
         protected $customLogger;
     
         public function __construct(
             \Magento\Framework\App\Action\Context $context,
             Monolog $customLogger
         ) {
             $this->customLogger = $customLogger;
             parent::__construct($context);
         }
     
         public function execute()
         {
             $this->customLogger->addDebug('Debug message', ['source' => 'CustomLog']);
             $this->customLogger->addDebug(print_r($someVariable, true), ['source' => 'CustomLog']);
             // Your code here
         }
     }

4. Using PHP’s debug_backtrace(): If you want to print a debug trace to understand the flow, you can use PHP’s built-in debug_backtrace() function.

   <?php
   $debugTrace = debug_backtrace();
   $this->logger->debug(print_r($debugTrace, true));

5. Error Handling: To catch and log exceptions, you can use try-catch blocks and log the exception details.

   <?php
   try {
       // Your code here
   } catch (\Exception $e) {
       $this->logger->error('Error: ' . $e->getMessage());
       $this->logger->error('Trace: ' . $e->getTraceAsString());
   }

6. Check Logs: After logging, check the var/log/system.log or your custom log file in the var/log directory for the logged messages and debug traces.
7. By following these steps, you can print debug traces and log error details in Magento 2 to help you troubleshoot issues effectively.

$traces = debug_backtrace();
foreach($traces as $trace){
    var_dump($trace['class'] . '::' . $trace['function'] . '('.$trace['line'] .')');
}
die();

You can print any object data by following code

echo "<pre>";
print_r(json_decode(json_encode($quote->getData())));
exit;