diff --git a/config.xml b/config.xml
index 0b35bc461..0fb53b7b8 100644
--- a/config.xml
+++ b/config.xml
@@ -27,7 +27,7 @@
     <preference name="UIWebViewBounce" value="false" />
     <preference name="DisallowOverscroll" value="true" />
     <preference name="prerendered-icon" value="true" />
-    <preference name="AppendUserAgent" value="MoodleMobile" />
+    <preference name="AppendUserAgent" value="MoodleMobile 4.0.0-dev (40000)" />
     <preference name="BackupWebStorage" value="none" />
     <preference name="ScrollEnabled" value="false" />
     <preference name="KeyboardDisplayRequiresUserAction" value="false" />
diff --git a/moodle.config.json b/moodle.config.json
index ecca950ae..84a52ba65 100644
--- a/moodle.config.json
+++ b/moodle.config.json
@@ -1,7 +1,7 @@
 {
     "app_id": "com.moodle.moodlemobile",
     "appname": "Moodle Mobile",
-    "versioncode": 4000,
+    "versioncode": 40000,
     "versionname": "4.0.0-dev",
     "cache_update_frequency_usually": 420000,
     "cache_update_frequency_often": 1200000,
diff --git a/upgrade.txt b/upgrade.txt
index ddb9fc2c5..11db21eef 100644
--- a/upgrade.txt
+++ b/upgrade.txt
@@ -3,6 +3,7 @@ information provided here is intended especially for developers.
 
 === 4.0.0 ===
 
+- The versioncode in moodle.config.json has changed from 4 digits to 5 digits to match the actual value for the stores: the 4.0.0 version's versioncode is now 40000 instead of 4000. If you maintain a Moodle plugin with mobile support and you use the versioncode that is sent in every request, you might need to check if this change will affect your code.
 - The parameters of the functions confirmAndPrefetchCourse and confirmAndPrefetchCourses have changed, they now accept an object with options.
 - Component core-navigation-bar changed to add an slider inside. previous, previousTitle, next, nextTitle, info and title have been removed.
   Now you have to pass all items and 3 optional params have been added.