diff --git a/core/lib/Drupal/Core/Database/DatabaseNotFoundException.php b/core/lib/Drupal/Core/Database/DatabaseAccessDeniedException.php
similarity index 52%
copy from core/lib/Drupal/Core/Database/DatabaseNotFoundException.php
copy to core/lib/Drupal/Core/Database/DatabaseAccessDeniedException.php
index 63eb9a3..a797fea 100644
--- a/core/lib/Drupal/Core/Database/DatabaseNotFoundException.php
+++ b/core/lib/Drupal/Core/Database/DatabaseAccessDeniedException.php
@@ -5,4 +5,4 @@
 /**
  * Exception thrown if specified database is not found.
  */
-class DatabaseNotFoundException extends \RuntimeException {}
+class DatabaseAccessDeniedException extends \RuntimeException implements DatabaseException {}
diff --git a/core/lib/Drupal/Core/Database/DatabaseNotFoundException.php b/core/lib/Drupal/Core/Database/DatabaseNotFoundException.php
index 63eb9a3..1c5b5eb 100644
--- a/core/lib/Drupal/Core/Database/DatabaseNotFoundException.php
+++ b/core/lib/Drupal/Core/Database/DatabaseNotFoundException.php
@@ -5,4 +5,4 @@
 /**
  * Exception thrown if specified database is not found.
  */
-class DatabaseNotFoundException extends \RuntimeException {}
+class DatabaseNotFoundException extends \RuntimeException implements DatabaseException {}
diff --git a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
index df51067..fd46438 100644
--- a/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/mysql/Connection.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Core\Database\Driver\mysql;
 
+use Drupal\Core\Database\DatabaseAccessDeniedException;
 use Drupal\Core\Database\DatabaseExceptionWrapper;
 
 use Drupal\Core\Database\Database;
@@ -27,6 +28,11 @@ class Connection extends DatabaseConnection {
   const DATABASE_NOT_FOUND = 1049;
 
   /**
+   * Error code for "Access denied" error.
+   */
+  const ACCESS_DENIED = 1045;
+
+  /**
    * Error code for "Can't initialize character set" error.
    */
   const UNSUPPORTED_CHARSET = 2019;
@@ -139,7 +145,18 @@ public static function open(array &$connection_options = array()) {
       $connection_options['pdo'] += [\PDO::MYSQL_ATTR_MULTI_STATEMENTS => FALSE];
     }
 
-    $pdo = new \PDO($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);
+    try {
+      $pdo = new \PDO($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);
+    }
+    catch (\PDOException $e) {
+      if ($e->getCode() == static::DATABASE_NOT_FOUND) {
+        throw new DatabaseNotFoundException($e->getMessage(), $e->getCode(), $e);
+      }
+      if ($e->getCode() == static::ACCESS_DENIED) {
+        throw new DatabaseAccessDeniedException($e->getMessage(), $e->getCode(), $e);
+      }
+      throw $e;
+    }
 
     // Force MySQL to use the UTF-8 character set. Also set the collation, if a
     // certain one has been set; otherwise, MySQL defaults to
diff --git a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
index 4688cde..042c221 100644
--- a/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/pgsql/Connection.php
@@ -4,6 +4,7 @@
 
 use Drupal\Core\Database\Database;
 use Drupal\Core\Database\Connection as DatabaseConnection;
+use Drupal\Core\Database\DatabaseAccessDeniedException;
 use Drupal\Core\Database\DatabaseNotFoundException;
 
 /**
@@ -27,6 +28,13 @@ class Connection extends DatabaseConnection {
   const DATABASE_NOT_FOUND = 7;
 
   /**
+   * Error code for "Access denied" error.
+   *
+   * Technically the error message is "insufficient_privilege".
+   */
+  const ACCESS_DENIED = '42501';
+
+  /**
    * The list of PostgreSQL reserved key words.
    *
    * @see http://www.postgresql.org/docs/9.4/static/sql-keywords-appendix.html
@@ -113,7 +121,19 @@ public static function open(array &$connection_options = array()) {
       // Convert numeric values to strings when fetching.
       \PDO::ATTR_STRINGIFY_FETCHES => TRUE,
     );
-    $pdo = new \PDO($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);
+
+    try {
+      $pdo = new \PDO($dsn, $connection_options['username'], $connection_options['password'], $connection_options['pdo']);
+    }
+    catch (\PDOException $e) {
+      if ($e->getCode() == static::DATABASE_NOT_FOUND) {
+        throw new DatabaseNotFoundException($e->getMessage(), $e->getCode(), $e);
+      }
+      if ($e->getCode() == static::ACCESS_DENIED) {
+        throw new DatabaseAccessDeniedException($e->getMessage(), $e->getCode(), $e);
+      }
+      throw $e;
+    }
 
     return $pdo;
   }
diff --git a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
index 2f5374b..10c63e8 100644
--- a/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
+++ b/core/lib/Drupal/Core/Database/Driver/sqlite/Connection.php
@@ -99,7 +99,19 @@ public static function open(array &$connection_options = array()) {
       // Convert numeric values to strings when fetching.
       \PDO::ATTR_STRINGIFY_FETCHES => TRUE,
     );
-    $pdo = new \PDO('sqlite:' . $connection_options['database'], '', '', $connection_options['pdo']);
+
+    try {
+      $pdo = new \PDO('sqlite:' . $connection_options['database'], '', '', $connection_options['pdo']);
+    }
+    catch (\PDOException $e) {
+      if ($e->getCode() == static::DATABASE_NOT_FOUND) {
+        throw new DatabaseNotFoundException($e->getMessage(), $e->getCode(), $e);
+      }
+      // SQLite doesn't have a distinct error code for access denied, so don't
+      // deal with that case.
+      throw $e;
+    }
+
 
     // Create functions needed by SQLite.
     $pdo->sqliteCreateFunction('if', array(__CLASS__, 'sqlFunctionIf'));
diff --git a/core/lib/Drupal/Core/Installer/CheckInstalledTrait.php b/core/lib/Drupal/Core/Installer/CheckInstalledTrait.php
index 8bbef6a..4fe8af8 100644
--- a/core/lib/Drupal/Core/Installer/CheckInstalledTrait.php
+++ b/core/lib/Drupal/Core/Installer/CheckInstalledTrait.php
@@ -4,7 +4,9 @@
 
 use Drupal\Core\Database\Connection;
 use Drupal\Core\Database\Database;
+use Drupal\Core\Database\DatabaseAccessDeniedException;
 use Drupal\Core\Database\DatabaseException;
+use Drupal\Core\Database\DatabaseNotFoundException;
 use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
 
 /**
@@ -41,6 +43,12 @@ protected function shouldRedirectToInstaller(\Exception $exception, Connection $
       return FALSE;
     }
 
+    // If the database wasn't found, assume the user hasn't entered it properly
+    // and redirect to the installer.
+    if ($exception instanceof DatabaseNotFoundException) {
+      return TRUE;
+    }
+
     // Never redirect if we're already in the installer.
     if (drupal_installation_attempted()) {
       return FALSE;
@@ -52,12 +60,6 @@ protected function shouldRedirectToInstaller(\Exception $exception, Connection $
       return TRUE;
     }
 
-    // A database error with code 1049 means "missing database", and it should
-    // be safe to redirect in that case.
-    if (($exception instanceof \PDOException || $exception instanceof DatabaseException) && $exception->getCode() == 1049) {
-      return TRUE;
-    }
-
     // Redirect if the database is empty.
     if ($connection) {
       try {
@@ -65,15 +67,14 @@ protected function shouldRedirectToInstaller(\Exception $exception, Connection $
       }
       catch (\Exception $e) {
         // If we still have an exception at this point, we need to be careful
-        // since we should not redirect if the exception represents an error on an
-        // already-installed site (for example, if the database server went down).
-        // Assume we shouldn't redirect, just in case.
+        // since we should not redirect if the exception represents an error on
+        // an already-installed site (for example, if the database server went
+        // down). Assume we shouldn't redirect, just in case.
         return FALSE;
       }
     }
 
-    // Default to FALSE to minimize the chance of overwriting an installed
-    // database.
+    // When in doubt, don't redirect.
     return FALSE;
   }
 }