400 bad request and utf8

Server NGINX
1

Hi,

Im using nginx and rails for my site which contains url with georgian
letters ie განცხადებები so something like

It is mainly working perfectly but sometimes I receive request with
truncated url ie
1 -
http://gancxadebebi.ge/ka/განცხადებებ��%9
(as u can see it should be something after %9)
or
2 -
http://gancxadebebi.ge/ka/განცხადებები?mc=mini+aipadi&search=ძიებ��%9

I succeeded to deal when there is no get parameters (first url above)
and make in that case a redirection to /
when this happen, this line is added to nginx error.log
2013/09/24 00:46:53 [alert] 63547#0: *19359227 pcre_exec() failed: -10
on “/ka/განცხადებებ�” using “”, client: aa.bb.cc.dd, server:
gancxadebebi.ge, request: “GET
/ka/%E1%83%92%E1%83%90%E1%83%9C%E1%83%AA%E1%83%AE%E1%83%90%E1%83%93%E1%83%94%E1%83%91%E1%83%94%E1%83%91%E1%8
HTTP/1.1”, host: “gancxadebebi.ge”

but for second url, which have get parameter truncated, I can not handle
that which generate a 400 bad request page.
such request added this line in nginx access.log
aa.bb.cc.dd - - [24/Sep/2013:00:48:47 +0200] “GET
/ka/%E1%83%92%E1%83%90%E1%83%9C%E1%83%AA%E1%83%AE%E1%83%90%E1%83%93%E1%83%94%E1%83%91%E1%83%94%E1%83%91%E1%83%98?mc=mini+aipadi&search=%E1%83%AB%E1%83%98%E1%83%94%E1%83%91%E1%83%
HTTP/1.1” 400 5 “-” “Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36
(KHTML, like Gecko) Chrome/29.0.1547.76 Safari/537.36”

does this mean that nginx accepted the request and then rails coudnt
resolve it ?

I don’t know if problem come from rails or from nginx. For first url, I
solved it in nginx conf
here part of my conf

access_log /var/log/nginx/gancx.access.log;
error_log /var/log/nginx/gancx.error.log;

client_body_in_file_only clean;
client_body_buffer_size 32K;
charset UTF-8;
source_charset UTF-8;
client_max_body_size 300M;



error_page  400 404         = @notfound;
error_page  500 502 504 = @server_error;
error_page  503         = @maintenance;

location @notfound {
  rewrite ^(.*)$ $scheme://$host permanent;
}

location @server_error {
    rewrite ^(.*)$ $scheme://$host permanent;
}

location @maintenance {
    rewrite ^(.*)$ $scheme://$host permanent;
}
sendfile on;
send_timeout 300s;

location / {
    proxy_pass http://gancx;
    proxy_redirect off;

    proxy_set_header   Host             $host;
    proxy_set_header   X-Real-IP        $remote_addr;
    proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
    charset UTF-8;
    client_max_body_size 7m;
    proxy_buffer_size          4k;
    proxy_buffers              4 32k;
    proxy_busy_buffers_size    64k;
    proxy_temp_file_write_size 64k;
}

thanks for your help