Error HTTP/1.1 400 Bad Request

Hello,
when I import a .OCS file, I have this message:
Error HTTP/1.1 400 Bad Request

I am going to see my file error_log and I have this line that appears:
[Wed Sep 27 15:40:01 2017] [error] [client 127.0.0.1] request failed: error reading the headers

I am under Centos and ocs 2.3.1

thank you