Merging stack consistently fails with message: "auto-merge was automatically disabled / Pull Request is not mergeable"

[bencdelaney]

We're just starting to use stacked PRs, and have run into issues while attempting to merge our first stack from the GitHub UI.

Our stack consists of four small changes, which we have successfully stacked and approved. The topmost PR indicates that the whole stack is ready to merge.

However, when I attempt to merge the stack, I consistently see this experience:

1. All four commits start spinning, as expected.

2. All four commits switch to the purple "merging" state, as expected.

3. This message appears in the PR conversation:

   

4. All four commits revert to their pre-merge state.

I don't see any further information regarding why the merge failed, so am unsure what we should try to resolve the issue.

[sumedha-lab]

CleanShot.2026-07-21.at.15.54.23.mp4

I encountered the same problem.

[steve-gore-snapdocs]

We are running into a similar issue. What are your branch protection setting?

[wolszews]

Also having the same issue

[skarim]

Hey all, thanks for the reports. We've identified a bug where approvals are not being appropriately evaluated when merging a stack of multiple PRs. We're actively investigating and will update when we've released a fix.

In the meantime, you can get around this by merging one PR at a time. I know it's not ideal, but hopefully that will unblock your workflows in the short-term. Appreciate your patience!