Here is example of how exceptions are printed in Drupal.
The website encountered an unexpected error. Please try again later.
Exception: Test in Drupal\system\Form\SiteInformationForm->buildForm() (line 96 of core/modules/system/src/Form/SiteInformationForm.php).
call_user_func_array() (Line: 534)
Drupal\Core\Form\FormBuilder->retrieveForm() (Line: 281)
Drupal\Core\Form\FormBuilder->buildForm() (Line: 73)
Drupal\Core\Controller\FormController->getContentResult()
call_user_func_array() (Line: 123)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 583)
Drupal\Core\Render\Renderer->executeInRenderContext() (Line: 121)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->wrapControllerExecutionInRenderContext() (Line: 97)
Drupal\Core\EventSubscriber\EarlyRenderingControllerWrapperSubscriber->Drupal\Core\EventSubscriber\{closure}() (Line: 163)
Symfony\Component\HttpKernel\HttpKernel->handleRaw() (Line: 74)
Symfony\Component\HttpKernel\HttpKernel->handle() (Line: 58)
Drupal\Core\StackMiddleware\Session->handle() (Line: 48)
Drupal\Core\StackMiddleware\KernelPreHandle->handle() (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass() (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle() (Line: 48)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle() (Line: 51)
Drupal\Core\StackMiddleware\StackedHttpKernel->handle() (Line: 698)
Drupal\Core\DrupalKernel->handle() (Line: 19)
There are a few issues with above output.
The main one is that it prints line numbers but no file names where those lines are located. Furthermore, if you try to locate those file by class names you will find that line numbers don't match the files. That's very confusing.
Another issue is how Error::formatBacktrace() renders arguments. It doesn't provide information about object types and
converts boolean to integers like follows.
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 58)
Such output is completely useless. Note that most users will unlikely see those arguments at all because arguments are only provided if zend.exception_ignore_args = On (since PHP 7.4). I guess most PHP installations have this value disabled by default (production mode).
Needs work
10.1 ✨
Last updated
Enhances developer experience.
The last submitted patch, 2: exception-backtrace-3353821-2.patch, failed testing. View results →
Applies the same formatting for PHP errors.
Given Error::formatBacktrace has no other usages besides tests it needs to be removed/deprecated.