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...', '/data/sites/jiaoyi51...', 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('user.id', null) in helper.php line 304
7. at session('user.id') in Article.php line 87
8. at Article->detail()
9. at ReflectionMethod->invokeArgs(object(Article), []) in App.php line 343
10. at App::invokeMethod([object(Article), 'detail'], []) in App.php line 595
11. at App::module([null, 'article', 'detail'], ['app_host' => '', 'app_debug' => true, 'app_trace' => false, ...], false) in App.php line 456
12. at App::exec(['type' => 'module', 'module' => [null, 'article', 'detail'], 'convert' => false], ['app_host' => '', 'app_debug' => true, 'app_trace' => false, ...]) in App.php line 139
13. at App::run() in start.php line 19
14. at require('/data/sites/jiaoyi51...') in index.php line 19