diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index b6c531c..ed15c60 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -41,6 +41,16 @@ define('ERROR_REPORTING_DISPLAY_SOME', 1);
 define('ERROR_REPORTING_DISPLAY_ALL', 2);
 
 /**
+ * Error reporting type of debug information: Add stacktrace or backtrace information to logs.
+ */
+define('ERROR_REPORTING_DISPLAY_LOGS', 1);  // Do not start at zero.
+
+/**
+ * Error reporting type of debug information: Add stacktrace or backtrace information to messages on page.
+ */
+define('ERROR_REPORTING_DISPLAY_MESSAGES', 2);
+
+/**
  * Indicates that the item should never be removed unless explicitly selected.
  *
  * The item may be removed using cache_clear_all() with a cache ID.
diff --git a/includes/errors.inc b/includes/errors.inc
index a9b7b5b..318531a 100644
--- a/includes/errors.inc
+++ b/includes/errors.inc
@@ -56,7 +56,8 @@ function _drupal_error_handler_real($error_level, $message, $filename, $line, $c
   if ($error_level & error_reporting()) {
     $types = drupal_error_levels();
     list($severity_msg, $severity_level) = $types[$error_level];
-    $caller = _drupal_get_last_caller(debug_backtrace());
+    $backtrace = debug_backtrace();
+    $caller = _drupal_get_last_caller($backtrace);
 
     if (!function_exists('filter_xss_admin')) {
       require_once DRUPAL_ROOT . '/includes/common.inc';
@@ -72,6 +73,7 @@ function _drupal_error_handler_real($error_level, $message, $filename, $line, $c
       '%file' => $caller['file'],
       '%line' => $caller['line'],
       'severity_level' => $severity_level,
+      '!backtrace' => $backtrace,
     ), $error_level == E_RECOVERABLE_ERROR);
   }
 }
@@ -112,14 +114,15 @@ function _drupal_decode_exception($exception) {
   $caller = _drupal_get_last_caller($backtrace);
 
   return array(
-    '%type' => get_class($exception),
+    '!backtrace'      => $backtrace,
+    '%type'           => get_class($exception),
     // The standard PHP exception handler considers that the exception message
     // is plain-text. We mimick this behavior here.
-    '!message' => check_plain($message),
-    '%function' => $caller['function'],
-    '%file' => $caller['file'],
-    '%line' => $caller['line'],
-    'severity_level' => WATCHDOG_ERROR,
+    '!message'        => check_plain($message),
+    '%function'       => $caller['function'],
+    '%file'           => $caller['file'],
+    '%line'           => $caller['line'],
+    'severity_level'  => WATCHDOG_ERROR,
   );
 }
 
@@ -162,9 +165,10 @@ function error_displayable($error = NULL) {
  * Logs a PHP error or exception and displays an error page in fatal cases.
  *
  * @param $error
- *   An array with the following keys: %type, !message, %function, %file, %line
- *   and severity_level. All the parameters are plain-text, with the exception
- *   of !message, which needs to be a safe HTML string.
+ *   An array with the following keys: %type, !message, %function, %file,
+ *   %line, severity_level, and backtrace. All the parameters are plain-text,
+ *   with the exception of !message, which needs to be a safe HTML string, and
+ *   backtrace, which is a standard PHP backtrace.
  * @param $fatal
  *   TRUE if the error is fatal.
  */
@@ -179,6 +183,13 @@ function _drupal_log_error($error, $fatal = FALSE) {
     drupal_maintenance_theme();
   }
 
+  // Backtrace array is not a valid replacement value for t().
+  $backtrace = isset($error['!backtrace']) ? $error['!backtrace'] : '';
+  unset($error['!backtrace']);
+  if (!$backtrace) {
+    $backtrace = debug_backtrace();
+  }
+
   // When running inside the testing framework, we relay the errors
   // to the tested site by the way of HTTP headers.
   $test_info = &$GLOBALS['drupal_test_info'];
@@ -199,7 +210,30 @@ function _drupal_log_error($error, $fatal = FALSE) {
     $number++;
   }
 
-  watchdog('php', '%type: !message in %function (line %line of %file).', $error, $error['severity_level']);
+  $st_opts=variable_get('error_stacktrace_display', array());
+  if (array_sum($st_opts)) {
+    $error['!stacktrace'] = format_stacktrace($backtrace);
+  }
+  $bt_opts=variable_get('error_backtrace_display', array());
+  if (array_sum($bt_opts)) {
+    $error['!backtrace'] = format_backtrace($backtrace);
+  }
+
+  if (!empty($st_opts[ERROR_REPORTING_DISPLAY_LOGS]) || !empty($bt_opts[ERROR_REPORTING_DISPLAY_LOGS])) {
+    $message_line='%type: <pre>!message</pre><br/>LINE: %line<br/>FUNCTION: %function<br/>FILE: %file';
+    if ($st_opts[ERROR_REPORTING_DISPLAY_LOGS]) {
+      $message_line .= ' !stacktrace';
+    }
+    if ($bt_opts[ERROR_REPORTING_DISPLAY_LOGS]) {
+      $message_line .= ' !backtrace';
+    }
+  }
+  else {
+    $message_line='%type: !message in %function (line %line of %file).';
+  }
+  if (!array_has_PDO_connection_exception($error)) {
+    watchdog('php', $message_line, $error, $error['severity_level']);
+  }
 
   if ($fatal) {
     drupal_add_http_header('Status', '500 Service unavailable (with message)');
@@ -229,13 +263,39 @@ function _drupal_log_error($error, $fatal = FALSE) {
       $class = 'error';
 
       // If error type is 'User notice' then treat it as debug information
-      // instead of an error message, see dd().
+      // instead of an error message.
+      // @see debug()
       if ($error['%type'] == 'User notice') {
         $error['%type'] = 'Debug';
         $class = 'status';
       }
 
-      drupal_set_message(t('%type: !message in %function (line %line of %file).', $error), $class);
+      // Attempt to reduce verbosity by removing DRUPAL_ROOT from the file path
+      // in the message. This does not happen for (false) security.
+      $root_length = strlen(DRUPAL_ROOT);
+      if (substr($error['%file'], 0, $root_length) == DRUPAL_ROOT) {
+        $error['%file'] = substr($error['%file'], $root_length + 1);
+      }
+      $message = t('%type: !message in %function (line %line of %file).', $error);
+
+      // Check if verbose error reporting is on.
+      $error_level = variable_get('error_level', ERROR_REPORTING_DISPLAY_ALL);
+
+      if ($error_level != ERROR_REPORTING_HIDE) {
+        if ($st_opts[ERROR_REPORTING_DISPLAY_MESSAGES]) {
+          $message .= $error['!stacktrace'];
+        }
+        if ($bt_opts[ERROR_REPORTING_DISPLAY_MESSAGES]) {
+          // First trace is the error itself, already contained in the message.
+          // While the second trace is the error source and also contained in the
+          // message, the message doesn't contain argument values, so we output it
+          // once more in the backtrace.
+          array_shift($backtrace);
+          // Generate a backtrace containing only scalar argument values.
+          $message .= '<pre class="backtrace">' . format_backtrace($backtrace) . '</pre>';
+        }
+      }
+      drupal_set_message($message, $class);
     }
 
     if ($fatal) {
@@ -252,12 +312,12 @@ function _drupal_log_error($error, $fatal = FALSE) {
  * Gets the last caller from a backtrace.
  *
  * @param $backtrace
- *   A standard PHP backtrace.
+ *   A standard PHP backtrace. Passed by reference.
  *
  * @return
  *   An associative array with keys 'file', 'line' and 'function'.
  */
-function _drupal_get_last_caller($backtrace) {
+function _drupal_get_last_caller(&$backtrace) {
   // Errors that occur inside PHP internal functions do not generate
   // information about file and line. Ignore black listed functions.
   $blacklist = array('debug', '_drupal_error_handler', '_drupal_exception_handler');
@@ -284,3 +344,131 @@ function _drupal_get_last_caller($backtrace) {
   }
   return $call;
 }
+
+/**
+ * We don't want to call watchdog() if anywhere in the array there is a
+ * PDOException because the database has gone away, in order to avoid an endless
+ * loop.
+ *
+ * The function will check for the exception and return TRUE if it finds it in
+ * an array. It checks recursively through the array.
+ *
+ * @param type $array
+ *   The array to check, will likely be $error from calling function
+ *
+ * @return boolean
+ *   TRUE if found.
+ */
+function array_has_PDO_connection_exception($array) {
+  if (   array_key_exists('%type', $array)
+      && stripos($array['%type'], 'PDOException') !== FALSE
+      && array_key_exists('', $array)
+      && stripos($array['!message'], 'gone away') !== FALSE
+    ) {
+    return TRUE;
+  }
+  foreach ($array as $value) {
+    if (is_array($value) && array_has_PDO_connection_exception($value)) {
+      return TRUE;
+    }
+  }
+  return FALSE;
+}
+
+/**
+ * Formats a backtrace into a plain-text string.
+ *
+ * The calls show values for scalar arguments and type names for complex ones.
+ *
+ * @param array $backtrace
+ *   A standard PHP backtrace.
+ *
+ * @return string
+ *   A plain-text line-wrapped string ready to be put inside <pre>.
+ */
+function format_backtrace(array $backtrace) {
+  $return = '';
+  foreach ($backtrace as $trace) {
+    $call = array('function' => '', 'args' => array());
+    if (isset($trace['class'])) {
+      $call['function'] = $trace['class'] . $trace['type'] . $trace['function'];
+    }
+    elseif (isset($trace['function'])) {
+      $call['function'] = $trace['function'];
+    }
+    else {
+      $call['function'] = 'main';
+    }
+    if (isset($trace['args'])) {
+      foreach ($trace['args'] as $arg) {
+        if (is_scalar($arg)) {
+          $call['args'][] = is_string($arg) ? '\'' . filter_xss($arg) . '\'' : $arg;
+        }
+        else {
+          $call['args'][] = ucfirst(gettype($arg));
+        }
+      }
+    }
+    $return .= $call['function'] . '(' . implode(', ', $call['args']) . ")\n";
+  }
+  return '<br/><br/>BACKTRACE:<br/>' . $return;
+}
+
+/**
+ * Formats a stacktrace into an HTML table.
+ *
+ * @param array $backtrace
+ *   A standard PHP backtrace.
+ *
+ * @return string
+ *   An HTML string.
+ */
+function format_stacktrace(array $backtrace) {
+  $callstack = array_reverse($backtrace, TRUE);
+  // TODO: Styling should be in CSS or should make use of drupal's existing CSS.
+  $cs =<<<EOT
+<style>
+  .stacktrace td, .stacktrace th {padding: 0 0.5em;}
+  .stacktrace .row-bunch {border-top: 1px solid;}
+  pre.stacktrace {font-family: "Andale Mono","Courier New",Courier,Lucidatypewriter,Fixed,monospace;}
+</style>
+<pre class="stacktrace">
+  <table>
+    <thead>
+      <tr>
+        <th>Index</th>
+        <th>Function called</th>
+        <th>Caller line</th>
+        <th>Caller file</th>
+      </tr>
+    </thead>
+    <tbody>
+EOT
+  ;
+  $row_bunching=3;
+  foreach ($callstack AS $k => &$v) {
+    $row_bunching++;
+    if ($row_bunching >= 3) {
+      $row_class = 'class="row-bunch"';
+      $row_bunching=0;
+    } else {
+      $row_class = '';
+    }
+    $cs .= "<tr $row_class><td>$k</td>";
+    foreach (array('function'=>0, 'line'=>0, 'file'=>0) as $k2 => $v2) {
+      if (isset($v[$k2])) {
+        $data = str_replace(DRUPAL_ROOT . '/', '', $v[$k2]);
+        $data = htmlentities($data);
+        $cs .= "<td>$data</td>";
+      }
+    }
+    $cs .= '</tr>';
+  }
+  $cs .=<<<EOT
+    </tbody>
+  </table>
+</pre>
+EOT
+  ;
+  return '<br/><br/>STACKTRACE:' . $cs;
+}
diff --git a/modules/dblog/dblog.module b/modules/dblog/dblog.module
index 9183eed..c8c0405 100644
--- a/modules/dblog/dblog.module
+++ b/modules/dblog/dblog.module
@@ -144,20 +144,24 @@ function _dblog_get_message_types() {
  * Note: Some values may be truncated to meet database column size restrictions.
  */
 function dblog_watchdog(array $log_entry) {
-  Database::getConnection('default', 'default')->insert('watchdog')
-    ->fields(array(
-      'uid' => $log_entry['uid'],
-      'type' => substr($log_entry['type'], 0, 64),
-      'message' => $log_entry['message'],
-      'variables' => serialize($log_entry['variables']),
-      'severity' => $log_entry['severity'],
-      'link' => substr($log_entry['link'], 0, 255),
-      'location' => $log_entry['request_uri'],
-      'referer' => $log_entry['referer'],
-      'hostname' => substr($log_entry['ip'], 0, 128),
-      'timestamp' => $log_entry['timestamp'],
-    ))
-    ->execute();
+  if (!array_has_PDO_connection_exception($log_entry)) { // If it was a DB error don't write to the DB.
+    Database::getConnection('default', 'default')->insert('watchdog')
+      ->fields(array(
+        'uid' => $log_entry['uid'],
+        'type' => substr($log_entry['type'], 0, 64),
+        'message' => $log_entry['message'],
+        'variables' => serialize($log_entry['variables']),
+        'severity' => $log_entry['severity'],
+        'link' => substr($log_entry['link'], 0, 255),
+        'location' => $log_entry['request_uri'],
+        'referer' => $log_entry['referer'],
+        'hostname' => substr($log_entry['ip'], 0, 128),
+        'timestamp' => $log_entry['timestamp'],
+      ))
+      ->execute();
+  } else {
+    _drupal_log_error($log_entry, TRUE);
+  }
 }
 
 /**
diff --git a/modules/system/system.admin.inc b/modules/system/system.admin.inc
index 22c202c..1aa34f8 100644
--- a/modules/system/system.admin.inc
+++ b/modules/system/system.admin.inc
@@ -1676,6 +1676,28 @@ function system_logging_settings() {
     '#description' => t('It is recommended that sites running on production environments do not display any errors.'),
   );
 
+  $form['error_stacktrace_display'] = array(
+    '#type' => 'checkboxes',
+    '#title' => t('Choose how to monitor stacktrace information.'),
+    '#default_value' => variable_get('error_stacktrace_display', array()),
+    '#options' => array(
+      ERROR_REPORTING_DISPLAY_MESSAGES => t('Show on page'),
+      ERROR_REPORTING_DISPLAY_LOGS => t('Add to log'),
+    ),
+    '#description' => t('On production environments only use "Add to log" and then only when needed.'),
+  );
+
+  $form['error_backtrace_display'] = array(
+    '#type' => 'checkboxes',
+    '#title' => t('Choose how to monitor backtrace information.'),
+    '#default_value' => variable_get('error_backtrace_display', array()),
+    '#options' => array(
+      ERROR_REPORTING_DISPLAY_MESSAGES => t('Show on page'),
+      ERROR_REPORTING_DISPLAY_LOGS => t('Add to log'),
+    ),
+    '#description' => t('On production environments only use "Add to log" and then only when needed.'),
+  );
+
   return system_settings_form($form);
 }
 
