diff --git a/ChangeLog b/ChangeLog
index 7721d07405..27d8311ce7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -59,6 +59,7 @@ phpMyAdmin - ChangeLog
 - issue #12954 Fixed export of tracking data
 - issue #12960 Enclose exports in transaction by default
 - issue #12966 After adding a column ADD INDEX option won't be displayed when enabling AI
+- issue #12972 Better error message when Composer has not been run
 
 4.6.6 (2017-01-23)
 - issue #12759 Fix Notice regarding 'Undefined index: old_usergroup'
diff --git a/libraries/common.inc.php b/libraries/common.inc.php
index 2353eb4a2e..b0df7d9bee 100644
--- a/libraries/common.inc.php
+++ b/libraries/common.inc.php
@@ -75,6 +75,13 @@ require_once './libraries/vendor_config.php';
 /**
  * Activate autoloader
  */
+if (! @is_readable('./vendor/autoload.php')) {
+    die(
+        'File <tt>./vendor/autoload.php</tt> missing or not readable. <br />'
+        . 'Most likely you did not run Composer to '
+        . '<a href="https://docs.phpmyadmin.net/en/latest/setup.html#installing-from-git">install library files</a>.'
+    );
+}
 require_once './vendor/autoload.php';
 
 /**