# Error when trying to update the watchlist for a group via API (PUT groups/{id}.json)

**URL:** <https://meta.discourse.org/t/error-when-trying-to-update-the-watchlist-for-a-group-via-api-put-groups-id-json/393572>\
**Category:** Bug\
**Tags:** groups, rest-api\
**Created:** [January 15, 2026, 6:19pm UTC](https://meta.discourse.org/t/error-when-trying-to-update-the-watchlist-for-a-group-via-api-put-groups-id-json/393572 "2026-01-15T18:19:44Z")\
**Posts on this page:** 1\
**Showing post:** 1

<div class="post-metadata">

**Author:** ![apf](https://avatars.discourse-cdn.com/v4/letter/a/3da27b/32.png) [@apf](https://meta.discourse.org/u/apf)\
**Post date:** [January 15, 2026, 6:19pm UTC](https://meta.discourse.org/t/error-when-trying-to-update-the-watchlist-for-a-group-via-api-put-groups-id-json/393572/1 "2026-01-15T18:19:44Z")

</div>

**Priority/Severity** :

medium to high

**Platform:**

Python script as well as cURL command line

**Discourse server version:**

3.6.0.beta3-latest ([6adb4f8e84](https://github.com/discourse/discourse/commits/6adb4f8e845fd0a27880b3a1f6a74413dd22014f))

**Description** :

when trying to update the ‘watching\_category\_ids’ of an existing group, my python script (using simple “requests.put” reports the following error:

```plaintext
_doPut> ERROR from request: 422 Unprocessable Entity {‘user_count’: 2, ‘errors’: [‘You supplied invalid parameters to the request: update_existing_users’]}

```

even if there is no parameter called `update_existing_users` in my json data.

Using cURL to check via:

```plaintext
curl -k -L -X PUT -H 'api-key:xyz’ \
   -H 'api-username:system' \
   -H 'Accept:application/json;charset=utf-8' \
   -H 'Content-Type:application/json' \
   --data '{"group":{"name":"eb-chair-exo","watching_category_ids":[336,337]}}' \
   https://cms-phys-talk.web.cern.ch/groups/46.json

```

I get the same error:

```plaintext
{“user_count”:2,“errors”:[“You supplied invalid parameters to the request: update_existing_users”]}%

```

**Reproducible steps** :

```plaintext
curl -k -L -X PUT -H 'api-key:xyz’ \
   -H 'api-username:system' \
   -H 'Accept:application/json;charset=utf-8' \
   -H 'Content-Type:application/json' \
   --data '{"group":{"name":"eb-chair-exo","watching_category_ids":[336,337]}}' \
   https://cms-phys-talk.web.cern.ch/groups/46.json

```

* * *

edit: added discourse server version

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_[View the full topic](https://meta.discourse.org/t/error-when-trying-to-update-the-watchlist-for-a-group-via-api-put-groups-id-json/393572)._