fastcgi php nginx errorlog messed up

I have a strange problem, the errorlog of my nginx server is somehow messed up: PHP errors seem to be all written in one line and repeating itself recursively. This way the llog grows a few GB within one day! This is **one line** in the error log: 2020/03/26 16:58:45 [error] 29816#29816: *32 FastCGI sent in stderr: "PHP message: PHP Notice: Undefined variable: SCRIPT_FILENAME in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 58PHP message: PHP Notice: Undefined variable: pfad in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 60PHP message: PHP Notice: Undefined offset: 1 in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 65PHP message: PHP Notice: Undefined variable: benutzer in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 70PHP message: PHP Notice: Undefined index: PATH_TRANSLATED in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 84PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96PHP message: PHP Notice: Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on li The lines are cut after 2048 characters. here i split the lines before each new error:

2020/03/26 16:58:45 [error] 29816#29816: *32 FastCGI sent in stderr: "
PHP message: PHP Notice:  Undefined variable: SCRIPT_FILENAME in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 58
PHP message: PHP Notice:  Undefined variable: pfad in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 60
PHP message: PHP Notice:  Undefined offset: 1 in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 65
PHP message: PHP Notice:  Undefined variable: benutzer in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 70
PHP message: PHP Notice:  Undefined index: PATH_TRANSLATED in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 84
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on line 96
PHP message: PHP Notice:  Undefined variable: localdir in /var/kunden/webs/my_web_app/www/pics/userpics/index.php on li

Where could this come from? how do I have to define a standard error reporting in nginx?