The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator at admin@example.com to inform them of the time this error occurred, and the actions you performed just before this error.
More information about this error may be available in the server error log.
解决方法：
apache服务器没有开启URL重写模块，将注释去掉
在apache配置上，注意httpd.conf文件里：
//开启rewrite
LoadModule rewrite_module modules/mod_rewrite.so
LINUX下的xampp中的apache配置文件目录地址：
/opt/lampp/etc/httpd.conf Apache 配制文件。
CI当开启URL重写的时候，报错500 Internal Server Error
原文：http://www.cnblogs.com/kenshinobiy/p/4277449.html