diff --git a/course/format/social/version.php b/course/format/social/version.php
index 4e9200a..b4117e6 100644
--- a/course/format/social/version.php
+++ b/course/format/social/version.php
@@ -25,6 +25,6 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2015102100;        // The current plugin version (Date: YYYYMMDDXX)
+$plugin->version   = 2015051100;        // The current plugin version (Date: YYYYMMDDXX)
 $plugin->requires  = 2015050500;        // Requires this Moodle version
 $plugin->component = 'format_social';   // Full name of the plugin (used for diagnostics)
diff --git a/lib/classes/plugininfo/format.php b/lib/classes/plugininfo/format.php
index d0d161d..c266575 100644
--- a/lib/classes/plugininfo/format.php
+++ b/lib/classes/plugininfo/format.php
@@ -145,6 +145,32 @@ class format extends base {
 
         return $message;
     }
+    /**
+     * Returns the status of the plugin.
+     *
+     * Note this method was overriden for 29_STABLE beacuse there was a
+     * wrong version in format_social and we decided to fix it with a main
+     * upgrade step. The hack implemented here allows the installation/upgrade
+     * to continue normally for that exact wrong version (2015102100).
+     *
+     * See MDL-50119 for more information.
+     *
+     * @todo Delete this method in Moodle 3.0. It won't be needed anymore.
+     *
+     * @return string one of core_plugin_manager::PLUGIN_STATUS_xxx constants
+     */
+    public function get_status() {
+
+        // We need to intercept format_social because of MDL-50119.
+        if ($this->type === 'format' and $this->name === 'social' and
+            $this->versiondb === '2015102100' and $this->versiondisk < $this->versiondb) {
+                // Hack the result so we are allowed to continue and
+                // main upgrade does its job fixing the wrong version.
+                return core_plugin_manager::PLUGIN_STATUS_UPGRADE;
+        }
+
+        return parent::get_status();
+    }
 
     /**
      * Pre-uninstall hook.
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index d3c7f66..9a7429a 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -4375,5 +4375,14 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2015050401.00);
     }
 
+    if ($oldversion < 2015050500.02) {
+        // Downgrade format_social version from incorrect 2015102100 to correct 2015051100. See MDL-50119 for more info.
+        if (get_config('format_social', 'version') === '2015102100') {
+            set_config('version', '2015051100', 'format_social');
+        }
+
+        upgrade_main_savepoint(true, 2015050500.02);
+    }
+
     return true;
 }
diff --git a/version.php b/version.php
index 95cd0ec..e15b4b5 100644
--- a/version.php
+++ b/version.php
@@ -29,7 +29,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$version  = 2015050500.01;              // YYYYMMDD      = weekly release date of this DEV branch.
+$version  = 2015050500.02;              // YYYYMMDD      = weekly release date of this DEV branch.
                                         //         RR    = release increments - 00 in DEV branches.
                                         //           .XX = incremental changes.