API v2 returning duplicate entry's

[mhuijser-dc]

Which Umbraco version are you using? (Please write the exact version, example: 10.1.0)

15.2.2

Bug summary

We're encountering an issue with the Umbraco V2 API where a specific call returns multiple headers with the same value. In the CMS, the values are configured correctly, but the data received from the API doesn't match what’s set in the CMS. We suspect this might be related to the blueprints used in Umbraco, but we haven't been able to confirm it yet.

Specifics

Steps to reproduce

Steps to Reproduce

Check CMS Configuration

Open the Umbraco CMS.
Navigate to the section where the headers are configured.
Verify that the expected value (e.g., "Detail page header") appears only once.
Execute the API Call

Make the following API request:

GET https://umbraco.io/umbraco/delivery/api/v2/content?fetch=children:&fields=properties[$all[properties[$all[properties[$all]]]]]&sort=createDate:desc&skip=24&take=12

Use a tool like Postman, cURL, or the browser console to execute the request.

Inspect the Response

Look at the response payload, specifically the headers.
Identify if "Detail page header" appears multiple times in the generic header where it should only appear once.

Compare with CMS Data

Check if the response values match what is configured in the CMS.
If they do not, note the discrepancies.

Investigate Umbraco Blueprints (If Applicable)

If content is created from a Blueprint, verify whether the blueprint contains duplicate header values.
Try creating a new item without using a blueprint and see if the issue persists.

Determine if other headers also have duplicated values or if this is isolated to "Detail page header".
If other headers are affected, the issue might be a general duplication problem in the API.

Expected result / actual result

Expected Behavior:
The "Article page title" value should appear only once in the appropriate header.

Actual Behavior:
The value appears multiple times where it should only appear once.

Potential Causes:
Umbraco Blueprints might be duplicating data.
An issue in the API response processing.
Data corruption or unintended duplication in the CMS.

---

This item has been added to our backlog AB#50330

[github-actions]

Hi there @mhuijser-dc!

Firstly, a big thank you for raising this issue. Every piece of feedback we receive helps us to make Umbraco better.

We really appreciate your patience while we wait for our team to have a look at this but we wanted to let you know that we see this and share with you the plan for what comes next.

• We'll assess whether this issue relates to something that has already been fixed in a later version of the release that it has been raised for.
• If it's a bug, is it related to a release that we are actively supporting or is it related to a release that's in the end-of-life or security-only phase?
• We'll replicate the issue to ensure that the problem is as described.
• We'll decide whether the behavior is an issue or if the behavior is intended.

We wish we could work with everyone directly and assess your issue immediately but we're in the fortunate position of having lots of contributions to work with and only a few humans who are able to do it. We are making progress though and in the meantime, we will keep you in the loop and let you know when we have any questions.

Thanks, from your friendly Umbraco GitHub bot 🤖 🙂

[AndyButland]

Could you give a bit more detail on this step please @mhuijser-dc?

Navigate to the section where the headers are configured.

Sorry if this ends up being me missing something obvious, but I'm not clear what you mean here.