For a few weeks now Bugbot has not been recognizing changes in PRs.
Specifically, I create a new PR and Bugbot runs but instead of adding a message to the PR description it shows “No changes detected in the provided diff; no code, config, or asset modifications identified.”. It then finishes within seconds saying there are not bugs. Normally, it’s at least a few minutes for Bugbot to run.
Hey, thanks for the report. This is a bug. If the diff is truly empty, a verbose run shouldn’t take 2+ minutes.
I’ll pass the request ID to the team to investigate. Can you share a link to this PR (or any other one where this reproduces)? That’ll help the engineers check what exactly is coming in the diff.
The GitHub App was installed 2 days ago (after the reinstall).
Bugbot says “for commit 2d5153e”, which is the latest commit in the PR.
A couple of questions to narrow this down:
Does anyone else in your GitHub org have their own Cursor account?
In your GitHub org settings (Settings > Applications > Installed GitHub Apps), how many Cursor installations do you see?
Commit 2d5153e (“Fixed call to getUserDomainIds”), was that a big commit or a small fix?
If there are multiple Cursor installations in the org, routing might be going through the wrong one. A workaround is to remove all installations and reinstall from a single account.
No, no one else has their own Cursor account. I’m the only one with a Cursor account. In fact, I’m the only one with access to the repositories (I’m a development team of 1).
Below is a screenshot of a PR where Bugbot performed correctly. My typical workflow is that once I’m done with a branch, I’ll do a PR. There are usually a number of commits. Bugbot would normally generate a description and check the code for issues. The whole process would take anywhere from 2 - 8 minutes. Sometimes a bug is found and sometimes not. If I add more commits Bugbot would recognize that and test again. Currently, Bugbot doesn’t seem to recognize that there are any changes whether from the the initial PR or additional code commits pushed to the PR.
Commit 2d5153e was a small commit. However, that was the last commit before the PR was created. Bugbot should have analyzed the entire PR, not just that commit, like it had before. It doesn’t seem to matter if the last commit was big or small.
The issues started for me on January 8, 2026 after 11:07 am. That was the last PR that I had that Bugbot correctly handled.
Thanks for the detailed info. The timing is really helpful. The issue started exactly on Jan 8 between 11:07 AM (last working) and 3:28 PM (first broken).
Since you only have one Cursor installation and you’re the only user, we can rule out a routing issue.
I shared your request ID and the full timeline with the engineering team. Since it started so suddenly on a specific day, it might be related to changes on the GitHub API side or our diff retrieval mechanism.
While the team is digging in, could you try one thing: create a new test PR with minimal changes, literally 1 to 2 lines, and see if Bugbot works on it? That’ll help us tell if it’s tied to diff size or if it’s a broader issue fetching any changes.
I’m keeping an eye on the engineers’ ticket and I’ll update the thread as soon as there’s progress.
Here are a few more request ids to test. These are for an existing PR. I intentionally created the PR for a branch that is still in progress to test Bugbot. It did three checks, all of them finishing quickly with no detection of changes.
I created a small PR as you requested. I changed two lines of PHP code and put in intentional bugs. Bugbot request: serverGenReqId_82b4177e-aef3-4d00-b3cb-df714ae3b51c
Bugbot seemed to detect the changes and wrote a PR description. It then found 1 of two bugs. Considering how small the changes are and the obvious bugs, they should have been found. But, it is good that in this case Bugbot ran correctly.
I then went back to the existing PR that BugBot has checked four times and did a similar small commit with two lines changed and two intentional bugs. The request id is serverGenReqId_34818bc0-d9ad-44fd-900a-ae35d0b3e5da.
In this case, with the existing PR, bugbot detected no changes and didn’t detect the bugs.
Great job with the tests, this info is really important. The pattern is now completely clear:
New PR with a small commit: works correctly
Existing PR + a new small commit: “No changes detected”
This strongly points to an issue in how the diff is fetched for existing PRs. I shared all the request IDs and your test results with the team, so they now have clear steps to reproduce it.
Timing is also a useful hint. Your issue started on January 8, right when a critical fix to the bugbot infrastructure was deployed. It could be an unintended side effect.
The team is working on it. I’ll update the thread as soon as there’s progress.
