[V15] Child content types are broken

[arknu]

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

15.1.1

Bug summary

In v13 and previous versions, you can create children of existing content types:

In v15 the create option is nowhere to be found:

Existing child content types are present, but give an error when saving:

{
    "type": "Error",
    "title": "Duplicate property type alias",
    "status": 400,
    "detail": "One or more property type aliases are already in use, all property type aliases must be unique.",
    "operationStatus": "DuplicatePropertyTypeAlias"
}

It seems that someone forgot that this feature even existed when creating the new backoffice, thus leading to problems when upgrading sites.

I assume this is accidental and not yet another attempt to remove this useful feature. We tried that once, remember?

Specifics

No response

Steps to reproduce

Try creating a child of an existing content type in v15. Note that the menu option to do that is missing.

Expected result / actual result

You should be able to create the child content type, as in v13.

[github-actions]

Hi there @arknu!

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 🤖 🙂

[leekelleher]

@arknu Thank you for reporting this. The nested document type feature is definitely on our radar. An issue has already reported about it in #16872. I'll close this one off so to focus any discussions on that ticket.