Sentry intergation with slim framework

Hi all, We have project that been done by someone and delivered to us and has small issues: - When it is integrated with sentry it will start reporting to [login to view URL] but the page will not loaded correctly. - it has session /cookie issue where website is not remembering user account - He has some cache functionality but we don't know how to be used - website producing this error Warning: ini_set(): A session is active. You cannot change the session module's ini settings at this time in /var/www/html/app/api/vendor/bryanjhv/slim-session/src/Slim/Middleware/[login to view URL] on line 129 Fatal error: Uncaught RuntimeException: Unexpected data in output buffer. Maybe you have characters before an opening <?php tag? in /var/www/html/app/api/vendor/slim/slim/Slim/[login to view URL] Stack trace: #0 /var/www/html/app/api/vendor/slim/slim/Slim/[login to view URL](317): Slim\App->finalize(Object(Slim\Http\Response)) #1 /var/www/html/app/[login to view URL](7): Slim\App->run() #2 {main} thrown in /var/www/html/app/api/vendor/slim/slim/Slim/[login to view URL] on line 621 I need someone who has fair experience to help us to fix issue, we are expecting long time cooperation for the one who will try to solve out the issue as we having many many things else. here is our composer { "require": { "slim/slim": "^3.0", "slim/twig-view": "^2.4", "illuminate/database": "^5.2", "respect/validation": "^1.1", "slim/csrf": "0.8.3", "slim/flash": "^0.1.0", "firebase/php-jwt": "^3.0", "swiftmailer/swiftmailer": "^6.0", "rmccue/requests": "^1.7", "santigarcor/laratrust": "3.0.*", "duccio/apns-php": "^1.0", "jwage/php-apns": "^0.0.3", "bryanjhv/slim-session": "~3.0", "symfony/filesystem": "3.4", "vlucas/phpdotenv": "^4.1", "robmorgan/phinx": "^0.11.4", "php-http/httplug": "^1.1.0", "guzzlehttp/guzzle": "^6.5", "slim/views": "^0.1.3", "illuminate/pagination": "~5.0" }, "autoload": { "psr-4": { "App\\": "app" } }, "require-dev": { "symfony/var-dumper": "3.4" } }