[Koha] koha 2.2.8 + ubuntu

hi i'm tried to install koha 2.2.8 on ubuntu and i finished installation and can't open opac or intranet give me this page .. any help thank's Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request. Please contact the server administrator, admin@root and inform them of the time the error occurred, and anything you might have done that may have caused the error. More information about this error may be available in the server error log. ________________________________