Well according to my google search the problem is your webserver. What webserver (and version) are you running? What version of osTicket?source: http://100pulse.com/http-statuscode/505.jsppertinent text:505 Error Code ExplainedThe server does not support the HTTP protocol version used in the request.
Why it occursThe Web server does not support, or refuses to support, the HTTP protocol version specified by the client in the HTTP request data stream sent to the server. The HTTP protocol has various versions identified as major and minor, e.g. version 0.9, 1.0 or 1.1. The server is indicating that it is unable or unwilling to complete the request using the major version provided by the client.Fixing 505 error codeThe only option to fix this error is to upgrade the Web server software to the higher version.Because the lower versions provide poorer security and performance than newer versions of the protocol.