diff --git a/src/ldapserver.js b/src/ldapserver.js
index fc96b8b5e..ed872e19d 100644
--- a/src/ldapserver.js
+++ b/src/ldapserver.js
@@ -510,6 +510,7 @@ async function userSearchSftp(req, res, next) {
 
     const [error, app] = await safe(apps.getByFqdn(appFqdn));
     if (error) return next(new ldap.OperationsError(error.message));
+    if (!app) return next(new ldap.OperationsError('Invalid app'));
 
     // only allow apps which specify "ftp" support in the localstorage addon
     if (!safe.query(app.manifest.addons, 'localstorage.ftp.uid')) return next(new ldap.UnavailableError('Not supported'));