diff --git a/public/main/install/index.php b/public/main/install/index.php
index cf10e023600..a6237b683a6 100644
--- a/public/main/install/index.php
+++ b/public/main/install/index.php
@@ -70,6 +70,58 @@
 Container::$session = new HttpSession();
 
 require_once 'install.lib.php';
+
+$envFile = api_get_path(SYMFONY_SYS_PATH).'.env';
+$versionInfo = require __DIR__.'/version.php';
+$installerVersion = $versionInfo['new_version'] ?? null;
+
+if (file_exists($envFile)) {
+    $dotenv = new Dotenv();
+    try {
+        // Load .env without crashing if incomplete
+        $dotenv->loadEnv($envFile);
+    } catch (\Throwable $e) {
+        // Ignore and let the wizard continue
+    }
+
+    $appInstalled = (($_ENV['APP_INSTALLED'] ?? getenv('APP_INSTALLED') ?? '') === '1');
+
+    if ($appInstalled) {
+        // Try to read DB version; fail soft if DB is unreachable
+        $dbVersion = null;
+        try {
+            $dbHost = $_ENV['DATABASE_HOST'] ?? 'localhost';
+            $dbUser = $_ENV['DATABASE_USER'] ?? '';
+            $dbPass = $_ENV['DATABASE_PASSWORD'] ?? '';
+            $dbName = $_ENV['DATABASE_NAME'] ?? '';
+            $dbPort = (int) ($_ENV['DATABASE_PORT'] ?? 3306);
+
+            connectToDatabase($dbHost, $dbUser, $dbPass, $dbName, $dbPort);
+            $dbVersion = get_config_param_from_db('chamilo_database_version');
+        } catch (\Throwable $e) {
+            // Leave $dbVersion as null
+        }
+
+        // If DB version is >= installer version, block the wizard
+        if ($installerVersion && $dbVersion && version_compare($dbVersion, $installerVersion, '>=')) {
+            header('HTTP/1.1 409 Conflict');
+            echo '<!doctype html><meta charset="utf-8"><title>Chamilo already installed</title>';
+            echo '<div style="font-family:system-ui;max-width:760px;margin:64px auto;padding:24px;border:1px solid #e5e7eb;border-radius:12px">';
+            echo '<h1>Chamilo is already installed</h1>';
+            echo '<p>Database version: <strong>'.htmlspecialchars($dbVersion).'</strong>. '
+                .'Installer version: <strong>'.htmlspecialchars($installerVersion).'</strong>.</p>';
+            echo '<p>The install wizard is disabled because the platform is already installed and up-to-date.</p>';
+            echo '<p>If you need a fresh install, set <code>APP_INSTALLED=0</code> or remove <code>.env</code> first.</p>';
+            echo '</div>';
+            exit;
+        }
+
+        // If DB version < installer version, let the wizard run (upgrade path)
+        // If we could not read DB version (null), also allow the wizard (conservative).
+    }
+    // If APP_INSTALLED != 1, allow a fresh install
+}
+
 $httpRequest = Request::createFromGlobals();
 $installationLanguage = 'en_US';
 
diff --git a/public/main/install/install.lib.php b/public/main/install/install.lib.php
index cf4b17bb151..4c06c6ff85f 100644
--- a/public/main/install/install.lib.php
+++ b/public/main/install/install.lib.php
@@ -467,7 +467,7 @@ function display_requirements(
     $timezone = checkPhpSettingExists('date.timezone');
 
     $phpVersion = phpversion();
-    $isVersionPassed = version_compare($phpVersion, REQUIRED_PHP_VERSION, '<=') <= 1;
+    $isVersionPassed = version_compare($phpVersion, REQUIRED_PHP_VERSION, '>=');
 
     $extensions = [];
     $extensions[] = [
@@ -1800,17 +1800,55 @@ function checkCanCreateFile(string $file): bool
  */
 function isUpdateAvailable(): bool
 {
-    $dotenv = new Dotenv();
     $envFile = api_get_path(SYMFONY_SYS_PATH) . '.env';
-    $dotenv->loadEnv($envFile);
+    if (!file_exists($envFile)) {
+        return false; // No .env -> fresh install
+    }
+
+    $dotenv = new Dotenv();
+    try {
+        $dotenv->loadEnv($envFile);
+    } catch (\Throwable $e) {
+        // If .env cannot be parsed, play safe: no update banner
+        return false;
+    }
+
+    // Must be an installed platform
+    if (($_ENV['APP_INSTALLED'] ?? '') !== '1') {
+        return false;
+    }
 
-    // Check if APP_INSTALLED is set and equals '1'
-    if (isset($_ENV['APP_INSTALLED']) && $_ENV['APP_INSTALLED'] === '1') {
+    // Compare DB version vs installer version
+    $versionInfo = require __DIR__.'/version.php';
+    $installerVersion = $versionInfo['new_version'] ?? null;
+
+    if (!$installerVersion) {
+        // If we cannot know installer version, do not show update banner
+        return false;
+    }
+
+    $dbVersion = null;
+    try {
+        connectToDatabase(
+            $_ENV['DATABASE_HOST'] ?? 'localhost',
+            $_ENV['DATABASE_USER'] ?? '',
+            $_ENV['DATABASE_PASSWORD'] ?? '',
+            $_ENV['DATABASE_NAME'] ?? '',
+            (int) ($_ENV['DATABASE_PORT'] ?? 3306)
+        );
+        $dbVersion = get_config_param_from_db('chamilo_database_version');
+    } catch (\Throwable $e) {
+        // If DB is unreachable but platform is marked installed, allow upgrade path
+        // so the UI can guide the admin.
         return true;
     }
 
-    // If APP_INSTALLED is not found or not set to '1', assume the application is not installed
-    return false;
+    if (empty($dbVersion)) {
+        // No version recorded -> offer upgrade path to normalize state
+        return true;
+    }
+
+    return version_compare($dbVersion, $installerVersion, '<');
 }
 
 /**
