diff --git a/src/externalldap.js b/src/externalldap.js
index 20e2e9447..265b68da1 100644
--- a/src/externalldap.js
+++ b/src/externalldap.js
@@ -47,7 +47,13 @@ function getClientAndConfig(callback) {
     settings.getExternalLdapConfig(function (error, externalLdapConfig) {
         if (error) return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, error));
 
-        var client = ldap.createClient({ url: externalLdapConfig.url });
+        var client;
+        try {
+            client = ldap.createClient({ url: externalLdapConfig.url });
+        } catch (e) {
+            if (e instanceof ldap.ProtocolError) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'url protocol is invalid'));
+            return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, e));
+        }
 
         if (!externalLdapConfig.bindDn) return callback(null, client);
 
@@ -72,7 +78,13 @@ function testConfig(config, callback) {
     if (!config.baseDn) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'basedn must not be empty'));
     if (!config.filter) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'filter must not be empty'));
 
-    var client = ldap.createClient({ url: config.url });
+    var client;
+    try {
+        client = ldap.createClient({ url: config.url });
+    } catch (e) {
+        if (e instanceof ldap.ProtocolError) return callback(new ExternalLdapError(ExternalLdapError.BAD_FIELD, 'url protocol is invalid'));
+        return callback(new ExternalLdapError(ExternalLdapError.INTERNAL_ERROR, e));
+    }
 
     if (!config.bindDn) return callback(null, client);