Update to Drupal 8.0.0 beta 14. For more information, see https://drupal.org/node/2544542

.htaccess

@@ -18,9 +18,6 @@ Options -Indexes
 # Follow symbolic links in this directory.
 Options +FollowSymLinks
 
-# Make Drupal handle any 404 errors.
-ErrorDocument 404 /index.php
-
 # Set the default handler.
 DirectoryIndex index.php index.html index.htm
 
@@ -28,13 +25,14 @@ DirectoryIndex index.php index.html index.htm
 AddType image/svg+xml svg svgz
 AddEncoding gzip svgz
 
-# Override PHP settings that cannot be changed at runtime. See
+# Most of the following PHP settings cannot be changed at runtime. See
 # sites/default/default.settings.php and
 # Drupal\Core\DrupalKernel::bootEnvironment() for settings that can be
 # changed at runtime.
 
 # PHP 5, Apache 1 and 2.
 <IfModule mod_php5.c>
+  php_value assert.active                   0
   php_flag session.auto_start               off
   php_value mbstring.http_input             pass
   php_value mbstring.http_output            pass
@@ -62,6 +60,14 @@ AddEncoding gzip svgz
   </FilesMatch>
 </IfModule>
 
+# Set a fallback resource if mod_rewrite is not enabled. This allows Drupal to
+# work without clean URLs. This requires Apache version >= 2.2.16. If Drupal is
+# not accessed by the top level URL (i.e.: http://example.com/drupal/ instead of
+# http://example.com/), the path to index.php will need to be adjusted.
+<IfModule !mod_rewrite.c>
+  FallbackResource /index.php
+</IfModule>
+
 # Various rewrite rules.
 <IfModule mod_rewrite.c>
   RewriteEngine on
@@ -125,6 +131,9 @@ AddEncoding gzip svgz
   RewriteCond %{REQUEST_URI} !core
   RewriteRule ^ %1/core/%2 [L,QSA,R=301]
 
+  # Rewrite install.php during installation to see if mod_rewrite is working
+  RewriteRule ^core/install.php core/install.php?rewrite=ok [QSA,L]
+
   # Pass all requests not referring directly to files in the filesystem to
   # index.php.
   RewriteCond %{REQUEST_FILENAME} !-f