diff --git a/core/includes/errors.inc b/core/includes/errors.inc
index 707968b..31ed73f 100644
--- a/core/includes/errors.inc
+++ b/core/includes/errors.inc
@@ -159,7 +159,7 @@ function _drupal_log_error($error, $fatal = FALSE) {
     catch (\Exception $e) {
       // We can't log, for example because the database connection is not
       // available. At least try to log to PHP error log.
-      error_log(sprintf('Failed to log error: %type: !message in %function (line %line of %file).', $error['%type'], $error['%function'], $error['%line'], $error['%file']));
+      error_log(sprintf('Failed to log error: %s: %s in %s (line %d of %s).', $error['%type'], $error['!message'], $error['%function'], $error['%line'], $error['%file']));
     }
   }
 
diff --git a/core/modules/system/src/Tests/System/UncaughtExceptionTest.php b/core/modules/system/src/Tests/System/UncaughtExceptionTest.php
index 14b8bca..4d270dd 100644
--- a/core/modules/system/src/Tests/System/UncaughtExceptionTest.php
+++ b/core/modules/system/src/Tests/System/UncaughtExceptionTest.php
@@ -186,6 +186,35 @@ public function testLostDatabaseConnection() {
   }
 
   /**
+   * Tests fallback to PHP error log when an exception is thrown while logging.
+   */
+  public function testLoggerException() {
+    // Ensure the test error log is empty before these tests.
+    $this->assertNoErrorsLogged();
+
+    $this->expectedExceptionMessage = 'Deforestation';
+    \Drupal::state()->set('error_service_test.break_logger', TRUE);
+
+    $this->drupalGet('');
+    $this->assertResponse(500);
+    $this->assertText('The website encountered an unexpected error. Please try again later.');
+    $this->assertRaw($this->expectedExceptionMessage);
+
+    // Find fatal error logged to the simpletest error.log
+    $errors = file(\Drupal::root() . '/' . $this->siteDirectory . '/error.log', FILE_IGNORE_NEW_LINES | FILE_SKIP_EMPTY_LINES);
+    $this->assertIdentical(count($errors), 1, 'Exactly one line logged to the PHP error log');
+
+    $expected_path = \Drupal::root() . '/core/modules/system/tests/modules/error_service_test/src/MonkeysInTheControlRoom.php';
+    $expected_line = 61;
+    $expected_entry = "Failed to log error: Exception: Deforestation in Drupal\\error_service_test\\MonkeysInTheControlRoom->handle() (line ${expected_line} of ${expected_path})";
+    $this->assert(strpos($errors[0], $expected_entry) !== FALSE, 'Original error logged to the PHP error log when an exception is thrown by a logger');
+
+    // The exception is expected. Do not interpret it as a test failure. Not
+    // using File API; a potential error must trigger a PHP warning.
+    unlink(\Drupal::root() . '/' . $this->siteDirectory . '/error.log');
+  }
+
+  /**
    * {@inheritdoc}
    */
   protected function error($message = '', $group = 'Other', array $caller = NULL) {
diff --git a/core/modules/system/tests/modules/error_service_test/error_service_test.services.yml b/core/modules/system/tests/modules/error_service_test/error_service_test.services.yml
index 6ae4669..ef874e5 100644
--- a/core/modules/system/tests/modules/error_service_test/error_service_test.services.yml
+++ b/core/modules/system/tests/modules/error_service_test/error_service_test.services.yml
@@ -6,3 +6,8 @@ services:
   # Set up a service with a missing class dependency.
   broken_class_with_missing_dependency:
     class: Drupal\error_service_test\LonelyMonkeyClass
+  logger.broken:
+    class: Drupal\error_service_test\Logger\TestLog
+    tags:
+      - { name: logger }
+      - { name: backend_overridable }
diff --git a/core/modules/system/tests/modules/error_service_test/src/Logger/TestLog.php b/core/modules/system/tests/modules/error_service_test/src/Logger/TestLog.php
new file mode 100644
index 0000000..4c7723f
--- /dev/null
+++ b/core/modules/system/tests/modules/error_service_test/src/Logger/TestLog.php
@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\error_service_test\Logger\TestLog.
+ */
+
+namespace Drupal\error_service_test\Logger;
+
+use Drupal\Core\Logger\RfcLoggerTrait;
+use Psr\Log\LoggerInterface;
+
+/**
+ * Throws an exception while logging an exception.
+ *
+ * @see \Drupal\system\Tests\System\UncaughtExceptionTest::testLoggerException()
+ */
+class TestLog implements LoggerInterface {
+  use RfcLoggerTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function log($level, $message, array $context = array()) {
+    $trigger = [
+      '%type' => 'Exception',
+      '!message' => 'Deforestation',
+      '%function' => 'Drupal\error_service_test\MonkeysInTheControlRoom->handle()',
+      'severity_level' => 3,
+      'channel' => 'php',
+    ];
+    if (array_diff_assoc($trigger, $context) === []) {
+      throw new \Exception('Oh, oh, frustrated monkeys!');
+    }
+  }
+
+}
diff --git a/core/modules/system/tests/modules/error_service_test/src/MonkeysInTheControlRoom.php b/core/modules/system/tests/modules/error_service_test/src/MonkeysInTheControlRoom.php
index 03b2b69..f780d29 100644
--- a/core/modules/system/tests/modules/error_service_test/src/MonkeysInTheControlRoom.php
+++ b/core/modules/system/tests/modules/error_service_test/src/MonkeysInTheControlRoom.php
@@ -57,6 +57,10 @@ public function handle(Request $request, $type = self::MASTER_REQUEST, $catch =
       throw new \Exception('Oh oh, bananas in the instruments.');
     }
 
+    if (\Drupal::state()->get('error_service_test.break_logger')) {
+      throw new \Exception('Deforestation');
+    }
+
     return $this->app->handle($request, $type, $catch);
   }