From the log
2016/10/19 11:26:41 [error] 9866#0: *236322 FastCGI sent in stderr: "PHP message: PHP Warning: preg_match(): Compilation failed: unmatched parentheses at offset 7 in /usr/share/nginx/www/spenden.wikimedia.de/release-20161019112245/src/Validation/TextPolicyValidator.php on line 118 PHP message: PHP Warning: preg_match(): Compilation failed: missing ) at offset 8 in /usr/share/nginx/www/spenden.wikimedia.de/release-20161019112245/src/Validation/TextPolicyValidator.php on line 118 PHP message: PHP Warning: preg_match(): Compilation failed: unmatched parentheses at offset 7 in /usr/share/nginx/www/spenden.wikimedia.de/release-20161019112245/src/Validation/TextPolicyValidator.php on line 118 PHP message: PHP Warning: preg_match(): Compilation failed: missing ) at offset 8 in /usr/share/nginx/www/spenden.wikimedia.de/release-20161019112245/src/Validation/TextPolicyValidator.php on line 118 PHP message: PHP Warning: preg_match(): Compilation failed: missing ) at offset 8 in /usr/share/nginx/www/spenden.wikimedia.de/release-20161019112245/src/Validation/TextPolicyValidator.php on line 118" while reading response header from upstream, client: 146.234.86.97, server: spenden.wikimedia.de, request: "POST /donation/add HTTP/1.1", upstream: "fastcgi://unix:/var/run/php/php7.0-fpm.sock:", host: "spenden.wikimedia.de", referrer: "https://spenden.wikimedia.de/donation/new?piwik_campaign=01-ba-161014&piwik_kwd=org-01-161014-ctrl"