closing Preview Mode causes an endless redirect loop

[shearer3000]

Which Umbraco version are you using?

15.4.0

Bug summary

When using content 'Save and Preview' and then clicking the 'End' button seems to put the browser in an endless redirect loop between two Umbraco urls. Important: this issue only affects content that's never been published before.

Specifics

From Chrome dev tools, there are approx 800 requests between two Umbraco urls e.g.

Steps to reproduce

1. start with a clean install of Umbraco
2. Set up two basic content trees (multisite structure with domain/hostname entered for each)
3. Set up a "Not Found" content type and pages in each content tree to represent a 404 not found page.
4. Add the NotFoundHandler as per https://docs.umbraco.com/umbraco-cms/reference/routing/request-pipeline/icontentfinder#notfoundhandlers
5. Create a new content page (never been published)
6. 'save and preview' to open the Preview Mode, and then click the End button (with browser network tab open to observe traffic)

reference for step 2:

Expected result / actual result

Expected: the End button closes the Preview mode tab
Actual: Umbraco puts the browser in a loop before eventually landing on the Not Found page

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This item has been added to our backlog AB#54097

[github-actions]

Hi there @shearer3000!

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 🤖 🙂

[NguyenThuyLan]

Thanks @shearer3000 , I was able to replicate it on 15.4.2 and 16.0.0-rc5.
The problem seems to be only with the End button when stopping Preview mode.
I can summarize the steps to repeat as follows:

1. Create a content page
2. Click save and preview
3. Open the Network tab (Devtool) to observe, then click the End button