Breadcrumb navigation completely broken in both Content and Media sections

[VegaMarinkovicAleksa]

Which Umbraco version are you using?

16.2.0

Bug summary

Backoffice breadcrumb links to the document editor are generated with a trailing /null variant segment and are not normalized to /invariant, causing the document workspace to show a 404 inside the main frame.

Specifics

Single-culture (invariant) site.
Breadcrumb anchor href ends with /null
Visiting the same URL without /null (or with /invariant) works as expected (just "/" normalizes to "/invariant")
This behaviour worked in v15 — /null was normalized to /invariant on navigation.
Fresh v16.2.0 install reproduces.

Steps to reproduce

• Install Umbraco 16.2.0 (fresh project).
• Create at least two document types: A and B.
• Make sure A is able to be created at root and allows the creation of B as its child.
• Create at least one node of each document type, ensuring that B nodes are children of A.
• Go to node B, and click on the link towards node A in the breadcrumbs at the bottom of the page (same section where "Save and preview", "Save", and "Save and publish" buttons are).

Expected result / actual result

Expected result
The router should normalize the variant segment and navigate to the editor at:
/umbraco/section/content/workspace/document/edit/{id}/invariant
…and the document workspace should load (tabs, groups, property editors, etc.).

Actual result
The URL remains with /null, the document workspace area shows a 404, and the expected set of workspace requests never fires.

^ Hovering over B link in the breadcrumbs (the actual URL is shown on the lower right)

[github-actions]

Hi there @VegaMarinkovicAleksa!

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]

Fixed via #20428 for 16.4 and 17.0.