>>> [!note] Migrated issue <!-- Drupal.org comment --> <!-- Migrated from issue #3563234. --> Reported by: [siva01](https://www.drupal.org/user/1600434) >>> <p>The issue is related to the stream setting for the chat block and RAG search. With a simple query like &ldquo;Hi,&rdquo; there is no issue. The problem occurs when I use RAG and streaming together. If streaming is disabled, RAG works without errors.</p> <p>Error:<br> RuntimeException: Failed to start the session because headers have already been sent by "/app/web/modules/contrib/ai/modules/ai_chatbot/src/Controller/DeepChatApi.php" at line 327. in Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage-&gt;start() (line 132 of /app/vendor/symfony/http-foundation/Session/Storage/NativeSessionStorage.php) </p>