"Something went wrong. Please try again." error appearing when merging MRs in gitlab.com since around 2023-04-17 - MRs appear to merge OK.

Summary

Several SaaS customers have this week reported the following error appearing whenever they merge an MR, despite the MR appearing to merge fine:

Links to ZenDesk tickets (internal GitLab access only):

• https://gitlab.zendesk.com/agent/tickets/397561
• https://gitlab.zendesk.com/agent/tickets/398061
• https://gitlab.zendesk.com/agent/tickets/398018

Steps to reproduce

Merge an MR.

Example Project

What is the current bug behavior?

Seemingly spurious error appears.

What is the expected correct behavior?

No error.

Relevant logs and/or screenshots

Output of checks

This bug happens on GitLab.com

Results of GitLab environment info

Expand for output related to GitLab environment info

(For installations with omnibus-gitlab package run and paste the output of:
`sudo gitlab-rake gitlab:env:info`)

(For installations from source run and paste the output of:
`sudo -u git -H bundle exec rake gitlab:env:info RAILS_ENV=production`)

Results of GitLab application Check

Expand for output related to the GitLab application check

(For installations with omnibus-gitlab package run and paste the output of:
sudo gitlab-rake gitlab:check SANITIZE=true)
(For installations from source run and paste the output of:
sudo -u git -H bundle exec rake gitlab:check RAILS_ENV=production SANITIZE=true)
(we will only investigate if the tests are passing)

Possible fixes