diff --git a/adminer/include/design.inc.php b/adminer/include/design.inc.php
index b1c3133e..d717769b 100644
--- a/adminer/include/design.inc.php
+++ b/adminer/include/design.inc.php
@@ -170,6 +170,7 @@ function get_nonce() {
 * @return null
 */
 function page_messages($error) {
+	global $adminer;
 	$uri = preg_replace('~^[^?]*~', '', $_SERVER["REQUEST_URI"]);
 	$messages = $_SESSION["messages"][$uri];
 	if ($messages) {
@@ -179,6 +180,9 @@ function page_messages($error) {
 	if ($error) {
 		echo "<div class='error'>$error</div>\n";
 	}
+	if ($adminer->error) { // separate <div>
+		echo "<div class='error'>$adminer->error</div>\n";
+	}
 }
 
 /** Print HTML footer
diff --git a/adminer/include/plugins.inc.php b/adminer/include/plugins.inc.php
index dc9cfe2d..d1e9fcb5 100644
--- a/adminer/include/plugins.inc.php
+++ b/adminer/include/plugins.inc.php
@@ -3,6 +3,7 @@ namespace Adminer;
 
 class Plugins extends Adminer {
 	public $plugins; ///< @var protected(set)
+	public $error = ''; ///< @var protected(set)
 
 	/** Register plugins
 	* @param array object instances or null to autoload plugins from adminer-plugins/
@@ -18,13 +19,23 @@ class Plugins extends Adminer {
 			}
 			if (file_exists("$basename.php")) {
 				$include = include_once "./$basename.php"; // example: return array(new AdminerLoginOtp($secret))
-				foreach ($include as $plugin) {
-					$plugins[get_class($plugin)] = $plugin;
+				if (is_array($include)) {
+					foreach ($include as $plugin) {
+						$plugins[get_class($plugin)] = $plugin;
+					}
+				} else {
+					$this->error .= lang('<b>%s</b> must return an array.', "$basename.php") . "<br>";
 				}
 			}
 			foreach (get_declared_classes() as $class) {
 				if (!$plugins[$class] && preg_match('~^Adminer\w~i', $class)) {
-					$plugins[$class] = new $class; // if the constructor have some required parameters then PHP triggers an error here
+					$reflection = new \ReflectionClass($class);
+					$constructor = $reflection->getConstructor();
+					if ($constructor && $constructor->getNumberOfRequiredParameters()) {
+						$this->error .= lang('Configure <b>%s</b> in <b>%s</b>.', $class, "$basename.php") . "<br>";
+					} else {
+						$plugins[$class] = new $class;
+					}
 				}
 			}
 		}
diff --git a/adminer/lang/cs.inc.php b/adminer/lang/cs.inc.php
index 8a760ce3..6ae4cc96 100644
--- a/adminer/lang/cs.inc.php
+++ b/adminer/lang/cs.inc.php
@@ -11,9 +11,11 @@ $translations = array(
 	'Login' => 'Přihlásit se',
 	'Logout' => 'Odhlásit',
 	'Logged as: %s' => 'Přihlášen jako: %s',
-	'Loaded plugins' => 'Nahrané pluginy',
 	'Logout successful.' => 'Odhlášení proběhlo v pořádku.',
 	'Thanks for using Adminer, consider <a href="https://www.adminer.org/en/donation/">donating</a>.' => 'Díky za použití Admineru, <a href="https://www.adminer.org/cs/donation/">přispějte</a> na vývoj.',
+	'Loaded plugins' => 'Nahrané pluginy',
+	'<b>%s</b> must return an array.' => '<b>%s</b> musí vracet pole.',
+	'Configure <b>%s</b> in <b>%s</b>.' => 'Nakonfigurujte <b>%s</b> v <b>%s</b>.',
 	'Invalid credentials.' => 'Neplatné přihlašovací údaje.',
 	'There is a space in the input password which might be the cause.' => 'Problém může být, že je v zadaném hesle mezera.',
 	'Adminer does not support accessing a database without a password, <a href="https://www.adminer.org/en/password/"%s>more information</a>.' => 'Adminer nepodporuje přístup k databázi bez hesla, <a href="https://www.adminer.org/cs/password/"%s>více informací</a>.',
diff --git a/adminer/lang/xx.inc.php b/adminer/lang/xx.inc.php
index d21ab09b..d0a4b5b5 100644
--- a/adminer/lang/xx.inc.php
+++ b/adminer/lang/xx.inc.php
@@ -11,9 +11,11 @@ $translations = array(
 	'Login' => 'Xx',
 	'Logout' => 'Xx',
 	'Logged as: %s' => 'Xx: %s',
-	'Loaded plugins' => 'Xx',
 	'Logout successful.' => 'Xx.',
 	'Thanks for using Adminer, consider <a href="https://www.adminer.org/en/donation/">donating</a>.' => 'Xx <a href="https://www.adminer.org/en/donation/">xx</a>.',
+	'Loaded plugins' => 'Xx',
+	'<b>%s</b> must return an array.' => '<b>%s</b> xx.',
+	'Configure <b>%s</b> in <b>%s</b>.' => 'Xx <b>%s</b> xx <b>%s</b>.',
 	'Invalid credentials.' => 'Xx.',
 	'There is a space in the input password which might be the cause.' => 'Xx.',
 	'Adminer does not support accessing a database without a password, <a href="https://www.adminer.org/en/password/"%s>more information</a>.' => 'Xx, <a href="https://www.adminer.org/en/password/"%s>xx</a>.',