配置文件 "config_global.php" 未找到或者无法访问

配置文件 "config_global.php" 未找到或者无法访问， 请确认您已经正确安装了程序

Program messages:

[Line: 0025]admin.php(discuz_core::instance) [Line: 0051]source/class/class_core.php(discuz_core->discuz_core) [Line: 0058]source/class/class_core.php(discuz_core->_init_config) [Line: 0260]source/class/class_core.php(system_error) [Line: 0018]source/function/function_core.php(discuz_error::system_error) [Line: 0024]source/class/class_error.php(discuz_error::debug_backtrace)

求具体解决步骤