Switching MR in non-Overview page between Draft and Ready using «more actions» dropdown ( ⋮ ) returns "Something went wrong. Please try again." (404)

Summary

Switching MR between Draft and Ready returns the error "Something went wrong. Please try again.", this happens specifically when:

1. Switching using «more actions» dropdown. Manually switching to draft/ready mode in the Edit MR page works.
2. Switching in a non-Overview MR page, it can happen in diffs, commits, and pipelines page. Switching on Overview MR page works.

In the logs or Developer Tools, it is returning 404, "route_not_found"

Steps to reproduce

1. Create a new MR as draft
2. Navigate to the Pipelines page
3. Click on the «more actions» dropdown ( ⋮ ) in the top right corner, mark MR as ready and the error show up

The «more actions» dropdown will show that the MR can now be switched back to draft, but the title still have "Draft:".

Example Project

What is the current bug behavior?

Switching MR to Draft/Ready using «more actions» dropdown in Commits/Pipelines/Changes page should work.

What is the expected correct behavior?

Switching MR to Draft/Ready using «more actions» dropdown in Commits/Pipelines/Changes page throw 404 error.

Relevant logs and/or screenshots

Kibana logs (internal only): https://log.gprd.gitlab.net/goto/4af0f080-0f18-11ee-a017-0d32180b1390

We only have 7-day worth of logs; we can see the issue starting from 2023/06/14, 6AM UTC.

Output of checks

This bug happens on GitLab.com

Possible fixes

This looks to be related to this MR deployed on Jun 14, 2023 11:13am UTC around when we start seeing increase in logs.

MR: !117298 (merged) Specifically !117298 (diffs)