I have updated my Magento 2.3.0 to 2.4.3, all through putty. All went fine, updated, upgraded, compiled, reindexed, cleared cache and everything. The problem is that on front end and backend is not working, and in the report I get this:
{"0":"Warning: Cannot modify header information - headers already sent by (output started at /home/customer/www/mywebsitename.net/public_html/app/design/frontend/MyTheme/my-theme/registration.php:1) in /home/customer/www/mywebsitename.net\/public_html/vendor/magento/framework/Stdlib/Cookie/PhpCookieManager.php on line 152","1":"#1 setcookie() called at [vendor/magento/framework/Stdlib/Cookie/PhpCookieManager.php:152]n#2 Magento\Framework\Stdlib\Cookie\PhpCookieManager->setCookie() called at [vendor/magento/framework/Stdlib/Cookie/PhpCookieManager.php:123]n#3 Magento\Framework\Stdlib\Cookie\PhpCookieManager->setPublicCookie() called at [vendor/magento/framework/App/PageCache/FormKey.php:74]n#4 Magento\Framework\App\PageCache\FormKey->set() called at [vendor/magento/module-page-cache/Plugin/RegisterFormKeyFromCookie.php:106]n#5 Magento\PageCache\Plugin\RegisterFormKeyFromCookie->updateCookieFormKey() called at [vendor/magento/module-page-cache/Plugin/RegisterFormKeyFromCookie.php:78]n#6 Magento\PageCache\Plugin\RegisterFormKeyFromCookie->beforeDispatch() called at [vendor/magento/framework/Interception/Interceptor.php:121]n#7 Magento\Framework\App\FrontController\Interceptor->Magento\Framework\Interception\{closure}() called at [vendor/magento/module-page-cache/Model/App/FrontController/BuiltinPlugin.php:75]n#8 Magento\PageCache\Model\App\FrontController\BuiltinPlugin->aroundDispatch() called at [vendor/magento/framework/Interception/Interceptor.php:135]n#9 Magento\Framework\App\FrontController\Interceptor->Magento\Framework\Interception\{closure}() called at [vendor/magento/framework/Interception/Interceptor.php:153]n#10 Magento\Framework\App\FrontController\Interceptor->___callPlugins() called at [generated/code/Magento/Framework/App/FrontController/Interceptor.php:23]n#11 Magento\Framework\App\FrontController\Interceptor->dispatch() called at [vendor/magento/framework/App/Http.php:116]n#12 Magento\Framework\App\Http->launch() called at [vendor/magento/framework/App/Bootstrap.php:263]n#13 Magento\Framework\App\Bootstrap->run() called at [pub/index.php:29]n","url":"/","script_name":"/pub/index.php","report_id":"d5eeac069811f2adaf2388327574b1f0928e8275f1fe58c17fd70b376b29e57b"}
Tryed already to check the registration.php file in my theme folder, and there is no characthers before <?php, and also is saved as UTF8, any idea?
