# Session\_start(): Failed to decode session object

**URL:** <https://discourse.cakephp.org/t/session-start-failed-to-decode-session-object/12062>\
**Category:** Need Help\
**Created:** [June 11, 2024, 1:08pm UTC](https://discourse.cakephp.org/t/session-start-failed-to-decode-session-object/12062 "2024-06-11T13:08:55Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![ProDaniBest](https://yyz1.discourse-cdn.com/flex029/user_avatar/discourse.cakephp.org/prodanibest/32/2521_2.png) [@ProDaniBest](https://discourse.cakephp.org/u/ProDaniBest)\
**Post date:** [June 11, 2024, 1:08pm UTC](https://discourse.cakephp.org/t/session-start-failed-to-decode-session-object/12062/1 "2024-06-11T13:08:55Z")

</div>

I use a DevContainer for developing my component with CakePHP 4. Quite normal: Docker with PHP 8.2 and MariaDB as the database. When I now call up my application, I get the following error:

**Error Message:**

```auto
Warning (2) : session_start(): Failed to decode session object. Session has been destroyed [in /workspaces/app/vendor/cakephp/cakephp/src/Http/Session.php, line 362]
Warning (512) : Unable to emit headers. Headers sent in file=/workspaces/app/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php line=37 [in /workspaces/app/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 71]
Warning (2) : Cannot modify header information - headers already sent by (output started at /workspaces/app/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /workspaces/app/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 164]
Warning (2) : Cannot modify header information - headers already sent by (output started at /workspaces/app/vendor/cakephp/cakephp/src/Error/Renderer/HtmlErrorRenderer.php:37) [in /workspaces/app/vendor/cakephp/cakephp/src/Http/ResponseEmitter.php, line 197]

```

Can someone give me a tip or a hint about what this error message is trying to tell me? I have checked everything and found nothing unusual.

My app settings are as follows:

```auto
'Session' => array(
    'defaults' => 'database',
    'timeout' => 15,
),

```

---

<div class="post-metadata">

**Author:** ![olivia0](https://yyz1.discourse-cdn.com/flex029/user_avatar/discourse.cakephp.org/olivia0/32/3152_2.png) [@olivia0](https://discourse.cakephp.org/u/olivia0)\
**Post date:** [June 12, 2024, 10:53am UTC](https://discourse.cakephp.org/t/session-start-failed-to-decode-session-object/12062/2 "2024-06-12T10:53:25Z")

</div>

Hey there,  
I guess the error message indicates a problem decoding session data, likely due to a serialization issue. Check for any output before session\_start(), review your database connection, and ensure the session table exists and is configured correctly. If the problem persists, consider debugging CakePHP’s session handling or seeking help from the CakePHP community.

---

<div class="post-metadata">

**Author:** ![ProDaniBest](https://yyz1.discourse-cdn.com/flex029/user_avatar/discourse.cakephp.org/prodanibest/32/2521_2.png) [@ProDaniBest](https://discourse.cakephp.org/u/ProDaniBest)\
**Post date:** [June 13, 2024, 5:29am UTC](https://discourse.cakephp.org/t/session-start-failed-to-decode-session-object/12062/3 "2024-06-13T05:29:20Z")

</div>

Thank you very much. I actually debugged everything completely and then was able to determine that the entries in the database were being deleted. After that, I discovered that the Devcontainer had the wrong time, causing all sessions to expire immediately. After updating the Devcontainer, everything is working again.