Site unavaliable after update to v1.7.35


I tried to update from 1.7.34 to 1.7.35 (offered in admin-browser) I have an error to open the site (admin and user).
The log of apache2:

[php:error] [pid 390] [client] PHP Fatal error:  
Uncaught Error: Failed opening required '/var/www/html/vendor/composer/../../system/defines.php' 
(include_path='.:/usr/share/php') in /var/www/html/vendor/composer/autoload_real.php:56\nStack trace:\n
#0 /var/www/html/vendor/composer/autoload_real.php(39): composerRequire0876d2626cf8275d40a570d03c63fabd()\n
#1 /var/www/html/vendor/autoload.php(12): ComposerAutoloaderInit0876d2626cf8275d40a570d03c63fabd::getLoader()\n
#2 /var/www/html/index.php(30): require('...')\n
#3 {main}\n  thrown in /var/www/html/vendor/composer/autoload_real.php on line 56

update: after download and copied v1.7.35 to webroot an restored /user/config/*, the system works again