FastCGI sent in stderr: "PHP message: PHP Warning:

Hello my system is:

Rasperry pi 2
PHP 7.0 fmp

the first login was successful, then from the control panel he saw some suggestions to change the settings of the php and from now the web page does not start anymore:
the log of ngnix is as follows:

2018/08/03 14:58:51 [error] 567#567: *3 FastCGI sent in stderr: “PHP message: PHP Warning: require(/var/www/nextcloud/3rdparty/composer/…/react/promise/src/functions_include.php): failed to open stream: No such file or directory in /var/www/nextcloud/3rdparty/composer/autoload_real.php on line 61
PHP message: PHP Fatal error: require(): Failed opening required ‘/var/www/nextcloud/3rdparty/composer/…/react/promise/src/functions_include.php’ (include_path=’/var/www/nextcloud/3rdparty/pear/console_getopt:/var/www/nextcloud/3rdparty/pear/pear_exception:/var/www/nextcloud/3rdparty/pear/pear-core-minimal/src:/var/www/nextcloud/3rdparty/pear/archive_tar:/var/www/nextcloud/apps’) in /var/www/nextcloud/3rdparty/composer/autoload_real.php on line 61” while reading response header from upstream, client:, server: cloud…com, request: “GET / HTTP/2.0”, upstream: “fastcgi://”, host: “…com”

Now I can not fix the problem, you could help me please.

Can anyone help me?