diff --git a/exec/lib/RemoteLoginUrlClient.php b/exec/lib/RemoteLoginUrlClient.php
index 08017ca..55248f3 100644
--- a/exec/lib/RemoteLoginUrlClient.php
+++ b/exec/lib/RemoteLoginUrlClient.php
@@ -96,7 +96,7 @@ final class RemoteLoginUrlClient
             throw new RuntimeException('Invalid process runner result');
         }
         if ($result->exitCode !== 0) {
-            throw new RuntimeException('MX helper failed');
+            throw new RuntimeException(self::failureMessage($settings, $result));
         }
         if (!preg_match('/https:\/\/\S+/', $result->stdout, $match)) {
             throw new RuntimeException('MX helper did not return a login URL');
@@ -108,6 +108,24 @@ final class RemoteLoginUrlClient
         }
     }
 
+    private static function failureMessage(Settings $settings, ProcessResult $result): string
+    {
+        $message = $settings->mxLoginMode() === 1 ? 'MX direct SSH command failed' : 'MX helper failed';
+        $message .= ' (exit ' . $result->exitCode . ')';
+        $detail = self::safeDiagnostic($result->stderr);
+        if ($detail !== '') {
+            $message .= ': ' . $detail;
+        }
+        return $message;
+    }
+
+    private static function safeDiagnostic(string $text): string
+    {
+        $text = preg_replace('/https?:\/\/\S+/i', '[redacted-url]', $text) ?? '';
+        $text = preg_replace('/\s+/', ' ', trim($text)) ?? '';
+        return substr($text, 0, 512);
+    }
+
     /**
      * @param list<string> $command
      */
diff --git a/plugin.conf b/plugin.conf
index 3e0567d..1f8d4cf 100644
--- a/plugin.conf
+++ b/plugin.conf
@@ -2,7 +2,7 @@ name=mail-login
 id=mail-login
 type=user
 author=HITME.PL
-version=1.0.5
+version=1.0.6
 active=no
 installed=no
 user_run_as=root
diff --git a/tests/package_contents_test.php b/tests/package_contents_test.php
index 0b67d23..3f539d5 100644
--- a/tests/package_contents_test.php
+++ b/tests/package_contents_test.php
@@ -8,7 +8,7 @@ test('plugin metadata and packaging docs match project rules', function (): void
     assert_contains('name=mail-login', $conf);
     assert_contains('id=mail-login', $conf);
     assert_contains('type=user', $conf);
-    assert_contains('version=1.0.5', $conf);
+    assert_contains('version=1.0.6', $conf);
     assert_contains('user_run_as=root', $conf);
     assert_contains('/Users/marek/GPT/ChatGPT/da_plugins/mail-login/src', $packing);
     assert_contains('/Users/marek/GPT/ChatGPT/da_plugins/mail-login/archives/X.Y.Z/mail-login.tar.gz', $packing);
diff --git a/tests/remote_login_url_client_test.php b/tests/remote_login_url_client_test.php
index b8df9ed..0ed682c 100644
--- a/tests/remote_login_url_client_test.php
+++ b/tests/remote_login_url_client_test.php
@@ -73,6 +73,26 @@ test('remote login url client validates helper output before returning it', func
     }
 });
 
+test('remote login url client reports direct ssh failure diagnostics', function (): void {
+    $settings = Settings::fromArray([
+        'MAIL_LOGIN_TARGET_BASE_URL' => 'https://mx1.domena.pl:2222',
+        'MX_LOGIN_MODE' => '1',
+    ]);
+    $request = new LoginUrlRequest('mxtest', 'h4.domena.pl', 'h4', 30, true, '198.51.100.10', '/', 1782810000);
+    $client = new RemoteLoginUrlClient(function (array $command, int $timeout): ProcessResult {
+        return new ProcessResult(255, '', "Host key verification failed.\n");
+    });
+
+    try {
+        $client->create($settings, $request);
+        throw new RuntimeException('Expected direct ssh failure to fail');
+    } catch (RuntimeException $e) {
+        assert_contains('MX direct SSH command failed', $e->getMessage());
+        assert_contains('exit 255', $e->getMessage());
+        assert_contains('Host key verification failed.', $e->getMessage());
+    }
+});
+
 test('process runner returns stdout and exit code from real command', function (): void {
     $result = RemoteLoginUrlClient::runProcess(['php', '-r', 'echo "ok\n";'], 5);