# Bad config encountered during initialization: The 'contents\_manager\_class' trait of a SingleUserLabApp instance expected a subclass of 'jupyter\_server.services.contents.manager.ContentsManager', not the S3ContentsManager S3ContentsManager

**URL:** <https://discourse.jupyter.org/t/bad-config-encountered-during-initialization-the-contents-manager-class-trait-of-a-singleuserlabapp-instance-expected-a-subclass-of-jupyter-server-services-contents-manager-contentsmanager-not-the-s3contentsmanager-s3contentsmanager/17304>\
**Category:** Zero to JupyterHub on Kubernetes\
**Tags:** help-wanted\
**Created:** [December 21, 2022, 5:54pm UTC](https://discourse.jupyter.org/t/bad-config-encountered-during-initialization-the-contents-manager-class-trait-of-a-singleuserlabapp-instance-expected-a-subclass-of-jupyter-server-services-contents-manager-contentsmanager-not-the-s3contentsmanager-s3contentsmanager/17304 "2022-12-21T17:54:55Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![lavanyasiva](https://avatars.discourse-cdn.com/v4/letter/l/8dc957/32.png) [@lavanyasiva](https://discourse.jupyter.org/u/lavanyasiva)\
**Post date:** [December 21, 2022, 5:54pm UTC](https://discourse.jupyter.org/t/bad-config-encountered-during-initialization-the-contents-manager-class-trait-of-a-singleuserlabapp-instance-expected-a-subclass-of-jupyter-server-services-contents-manager-contentsmanager-not-the-s3contentsmanager-s3contentsmanager/17304/1 "2022-12-21T17:54:55Z")

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Hi,  
I am trying to setup s3contentsmanager to save the notebooks in s3. Have jupyter\_server\_config.py at /etc/jupyter.While starting the user pod, it returns the following error message:  
**Bad config encountered during initialization: The ‘contents\_manager\_class’ trait of a SingleUserLabApp instance expected a subclass of ‘jupyter\_server.services.contents.manager.ContentsManager’, not the S3ContentsManager S3ContentsManager.**

Here’s the jupyter\_server\_config.py:

```auto
# Configuration file for jupyter-notebook.

from s3contents import S3ContentsManager
import os
user = os.environ['JUPYTERHUB_USER']
# Tell Jupyter to use S3ContentsManager for all storage.

c.ServerApp.contents_manager_class = S3ContentsManager
#c.ServerApp.root_dir = '/home/jovyan'
c.S3ContentsManager.bucket = os.environ['S3_BUCKET']
c.S3ContentsManager.region_name = os.environ['AWS_REGION']
c.S3ContentsManager.prefix = "{}/{}".format(os.environ['S3_PREFIX'], user)

```

Any help, please?

---

<div class="post-metadata">

**Author:** ![minrk](https://yyz1.discourse-cdn.com/flex031/user_avatar/discourse.jupyter.org/minrk/32/13_2.png) [@minrk](https://discourse.jupyter.org/u/minrk)\
**Post date:** [December 22, 2022, 9:06am UTC](https://discourse.jupyter.org/t/bad-config-encountered-during-initialization-the-contents-manager-class-trait-of-a-singleuserlabapp-instance-expected-a-subclass-of-jupyter-server-services-contents-manager-contentsmanager-not-the-s3contentsmanager-s3contentsmanager/17304/2 "2022-12-22T09:06:15Z")

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It looks like `s3contents` is [not compatible](https://github.com/danielfrg/s3contents/blob/881fc178dd7acadec274cafad1fa5e5f2def0264/s3contents/ipycompat.py#L39-L40) with jupyter-server or recent versions of jupyter-notebook (that are based on jupyter-server), only old versions of the jupyter-notebook server. You can opt-in to this with:

```yaml
singleuser:
  extraEnv:
    JUPYTERHUB_SINGLEUSER_APP: "notebook.notebookapp.NotebookApp"

```