5 files changed, 35 insertions, 0 deletions
diff --git a/phpBB/includes/acp/acp_extensions.php b/phpBB/includes/acp/acp_extensions.php
index aba9caaece..9bdd8eb458 100644
--- a/phpBB/includes/acp/acp_extensions.php
+++ b/phpBB/includes/acp/acp_extensions.php
@@ -137,6 +137,12 @@ class acp_extensions
 					trigger_error($user->lang['EXTENSION_NOT_AVAILABLE'] . adm_back_link($this->u_action), E_USER_WARNING);
 				}
 
+				$extension = $phpbb_extension_manager->get_extension($ext_name);
+				if (!$extension->is_enableable())
+				{
+					trigger_error($user->lang['EXTENSION_NOT_ENABLEABLE'] . adm_back_link($this->u_action), E_USER_WARNING);
+				}
+
 				if ($phpbb_extension_manager->is_enabled($ext_name))
 				{
 					redirect($this->u_action);
@@ -162,6 +168,12 @@ class acp_extensions
 					trigger_error($user->lang['EXTENSION_NOT_AVAILABLE'] . adm_back_link($this->u_action), E_USER_WARNING);
 				}
 
+				$extension = $phpbb_extension_manager->get_extension($ext_name);
+				if (!$extension->is_enableable())
+				{
+					trigger_error($user->lang['EXTENSION_NOT_ENABLEABLE'] . adm_back_link($this->u_action), E_USER_WARNING);
+				}
+
 				if ($phpbb_extension_manager->is_enabled($ext_name))
 				{
 					redirect($this->u_action);
diff --git a/phpBB/language/en/acp/extensions.php b/phpBB/language/en/acp/extensions.php
index 6ec722bb78..28cdc8829d 100644
--- a/phpBB/language/en/acp/extensions.php
+++ b/phpBB/language/en/acp/extensions.php
@@ -42,6 +42,7 @@ $lang = array_merge($lang, array(
 	'EXTENSION_INVALID_LIST'	=> 'The “%s” extension is not valid.<br />%s<br /><br />',
 	'EXTENSION_NOT_AVAILABLE'	=> 'The selected extension is not available for this board, please verify your phpBB and PHP versions are allowed (see the details page).',
 	'EXTENSION_DIR_INVALID'		=> 'The selected extension has an invalid directory structure and cannot be enabled.',
+	'EXTENSION_NOT_ENABLEABLE'	=> 'The selected extension cannot be enabled, please verify the extension’s requirements.',
 
 	'DETAILS'				=> 'Details',
 
diff --git a/phpBB/phpbb/extension/base.php b/phpBB/phpbb/extension/base.php
index cbbd7bc622..288fb7d19c 100644
--- a/phpBB/phpbb/extension/base.php
+++ b/phpBB/phpbb/extension/base.php
@@ -40,6 +40,7 @@ class base implements \phpbb\extension\extension_interface
 	*
 	* @param ContainerInterface $container Container object
 	* @param \phpbb\finder $extension_finder
+	* @param \phpbb\db\migrator $migrator
 	* @param string $extension_name Name of this extension (from ext.manager)
 	* @param string $extension_path Relative path to this extension
 	*/
@@ -54,6 +55,14 @@ class base implements \phpbb\extension\extension_interface
 	}
 
 	/**
+	* {@inheritdoc}
+	*/
+	public function is_enableable()
+	{
+		return true;
+	}
+
+	/**
 	* Single enable step that installs any included migrations
 	*
 	* @param mixed $old_state State returned by previous call of this method
diff --git a/phpBB/phpbb/extension/extension_interface.php b/phpBB/phpbb/extension/extension_interface.php
index cc8b8be980..6a6b6adb8f 100644
--- a/phpBB/phpbb/extension/extension_interface.php
+++ b/phpBB/phpbb/extension/extension_interface.php
@@ -20,6 +20,13 @@ namespace phpbb\extension;
 interface extension_interface
 {
 	/**
+	* Indicate whether or not the extension can be enabled.
+	*
+	* @return bool
+	*/
+	public function is_enableable();
+
+	/**
 	* enable_step is executed on enabling an extension until it returns false.
 	*
 	* Calls to this function can be made in subsequent requests, when the
diff --git a/phpBB/phpbb/extension/manager.php b/phpBB/phpbb/extension/manager.php
index b19eb9f8a3..5afec9ba82 100644
--- a/phpBB/phpbb/extension/manager.php
+++ b/phpBB/phpbb/extension/manager.php
@@ -177,6 +177,12 @@ class manager
 		$old_state = (isset($this->extensions[$name]['ext_state'])) ? unserialize($this->extensions[$name]['ext_state']) : false;
 
 		$extension = $this->get_extension($name);
+
+		if (!$extension->is_enableable())
+		{
+			return false;
+		}
+
 		$state = $extension->enable_step($old_state);
 
 		$active = ($state === false);