Redmine

Hello,

I am currently working on a Talend job that retrieves values from a database column and attempts to create or update a Custom Field in Redmine via the REST API.
My goal is to automatically create (or update) a custom field of type list, and dynamically populate its possible_values based on data retrieved from my database.

Context¶

• Talaxie version: 202511
• Redmine version: 6.0
• Authentication: API key (X-Redmine-API-Key header)
• REST endpoint used:
  • http://localhost/custom_fields.json
  • Content-Type: application/json

The issue

When I try to create a new custom field using: POST /custom_fields.json, with a JSON body like:

{
"custom_field": {
"name": "Agrement",
"field_format": "list",
"customized_type": "Issue",
"possible_values": ["A123456789"],
"is_required": false,
"is_filter": true
}
}

I receive: HTTP 403 Forbidden

So it appears that:

Listing custom fields is allowed
Creating or updating custom fields via REST is not permitted

Question¶

1. Is it expected behavior in Redmine 6.0 that custom fields can be retrieved via REST but cannot be created or updated via REST API?

If so:

2. Is there any supported way to programmatically update possible_values of a list custom field?
3. Or is this intentionally restricted to the administration UI only?

My use case requires dynamically maintaining the list of allowed values from an external data source (via Talaxie).

Any clarification or recommended approach would be greatly appreciated.

Thank you very much.