diff --git a/framework/core/src/Extension/ExtensionManager.php b/framework/core/src/Extension/ExtensionManager.php
index 7ac0f9a90..e9aaed950 100644
--- a/framework/core/src/Extension/ExtensionManager.php
+++ b/framework/core/src/Extension/ExtensionManager.php
@@ -73,12 +73,20 @@ class ExtensionManager
             // Load all packages installed by composer.
             $installed = json_decode($this->filesystem->get($this->app->vendorPath().'/composer/installed.json'), true);
 
+            // Composer 2.0 changes the structure of the installed.json manifest
+            $installed = $installed['packages'] ?? $installed;
+
             foreach ($installed as $package) {
                 if (Arr::get($package, 'type') != 'flarum-extension' || empty(Arr::get($package, 'name'))) {
                     continue;
                 }
+
+                $path = isset($package['install-path'])
+                    ? $this->getExtensionsDir().'/composer/'.$package['install-path']
+                    : $this->getExtensionsDir().'/'.Arr::get($package, 'name');
+
                 // Instantiates an Extension object using the package path and composer.json file.
-                $extension = new Extension($this->getExtensionsDir().'/'.Arr::get($package, 'name'), $package);
+                $extension = new Extension($path, $package);
 
                 // Per default all extensions are installed if they are registered in composer.
                 $extension->setInstalled(true);
diff --git a/framework/core/src/Install/Steps/EnableBundledExtensions.php b/framework/core/src/Install/Steps/EnableBundledExtensions.php
index 33d448906..14167e527 100644
--- a/framework/core/src/Install/Steps/EnableBundledExtensions.php
+++ b/framework/core/src/Install/Steps/EnableBundledExtensions.php
@@ -89,14 +89,22 @@ class EnableBundledExtensions implements Step
     private function loadExtensions()
     {
         $json = file_get_contents("$this->vendorPath/composer/installed.json");
+        $installed = json_decode($json, true);
 
-        return (new Collection(json_decode($json, true)))
+        // Composer 2.0 changes the structure of the installed.json manifest
+        $installed = $installed['packages'] ?? $installed;
+
+        return (new Collection($installed))
             ->filter(function ($package) {
                 return Arr::get($package, 'type') == 'flarum-extension';
             })->filter(function ($package) {
                 return ! empty(Arr::get($package, 'name'));
             })->map(function ($package) {
-                $extension = new Extension($this->vendorPath.'/'.Arr::get($package, 'name'), $package);
+                $path = isset($package['install-path'])
+                    ? "$this->vendorPath/composer/".$package['install-path']
+                    : $this->vendorPath.'/'.Arr::get($package, 'name');
+
+                $extension = new Extension($path, $package);
                 $extension->setVersion(Arr::get($package, 'version'));
 
                 return $extension;