session_start(): Cannot start session when headers already sent

Call Stack

1. in Session.php line 106
2. at Error::appError(2, 'session_start(): Can...', '/home/wwwroot/php-li...', 106, ['config' => ['id' => '', 'var_session_id' => '', 'prefix' => 'think', ...], 'isDoStart' => true])
3. at session_start() in Session.php line 106
4. at Session::init() in Session.php line 120
5. at Session::boot() in Session.php line 164
6. at Session::get('referer') in Backend.php line 205
7. at Backend->_initialize() in Index.php line 24
8. at Index->_initialize() in Controller.php line 59
9. at Controller->__construct(object(Request))
10. at ReflectionClass->newInstanceArgs([object(Request)]) in App.php line 359
11. at App::invokeClass('app\admin\controller...') in Loader.php line 479
12. at Loader::controller('index', 'controller', false, 'Error') in App.php line 580
13. at App::module(['admin', 'index', 'login'], ['app_host' => '', 'app_debug' => true, 'app_trace' => false, ...], true) in App.php line 456
14. at App::exec(['type' => 'module', 'module' => ['admin', 'index', 'login']], ['app_host' => '', 'app_debug' => true, 'app_trace' => false, ...]) in App.php line 139
15. at App::run() in start.php line 19
16. at require('/home/wwwroot/php-li...') in index.php line 24