Merging is blocked

    Merge is not an allowed merge method in this repository.
    This branch must not contain merge commits. 

Hmm, what does this mean?
I rebased things on master
a few times - doesn't help.

We prefer not introduce merge commits in the git history as they unnecessarily muddy up the git history.
So we have disabled merging PRs via git merge.
PRs are instead merged via git rebase, which adds the commits on top of the master branch without an additional merge commit, also keeping the history of the master branch linear.
Or "squashing", which is a form of rebase wherein the commits are combined into a single commit before being added on top of the master branch.

Sorry hit the wrong button when posting.

If you want additional information about the different PR merge options see this article in GitHub's documentation section.
https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/incorporating-changes-from-a-pull-request/about-pull-request-merges

If you are updating your PR branch from the GitHub web interface please make sure to select Update with rebase.

We unfortunately cannot turn off the git merge update option for that button, but it creates the same Git history mess as the git merge merge option for PRs.

But my branch doesn't have any
merge commits. And it is rebased
on top of master (although master
changes every minute).
So I assume it can be merged
with rebase strategy already.
So what actions are required on
my side to get rid of this blocking?

Oh, thanks, trying "Rebase branch".
But it says:

Response.json: Body has already been consumed.

I rebased locally (again) and
the button disappeared (again).
But merging is still blocked... :(

Switched to "Update with rebase"
and hit Rebase button.
This time it worked.
Still merging is blocked, nothing
changed. :(

I can't even demonstrate to
you that the branch is rebased,
as every minute the master
branch changes.

Oh, thanks, trying "Rebase branch". But it says:

Response.json: Body has already been consumed.

That seems to just be a visual bug.
I noticed it a couple times today.
Still seems to work just fine, maybe GitHub is having an issue with it in the backend.

I can't even demonstrate to you that the branch is rebased, as every minute the master branch changes.

Yeah we're still catching up on auto-updates since #22994 was just merged and the auto-update workflow reenabled.
It's working through the backlog, but this is a month's worth of auto updates compressed into a day.
So it's a lot busier than usual.

Ok but aven after local rebase
and force-push, merging is blocked.
Like it is now.

I'm not seeing that.
It should also be noted that you are not a Maintainer on this repository and as such do not have permissions to merge pull requests.

As you noted above, this PR is currently untested.
And it will require testing by either you or someone else familiar with the topic before it can be merged.

The message is:

Merging is blocked

    Merge is not an allowed merge method in this repository.
    This branch must not contain merge commits. 

But I guess if its not visible to
you, then its a false alarm.

This is what I'm seeing.

If I go to a repo where I do not have maintainer privilges and look at a PR I only get the CI run statistics

Here's mine.

Odd.
Might be an issue they haven't worked out with the new merge UI yet.

Correct!
Switching to old UI fixes the problem. :)
Thank you!