Code Reviewer cannot review a particular PR

[aaron_seet]

When we tested Code Reviewer on PRs it appears to be working as advertised inserting commentary about the code and its requirements fulfilment. But then a real PR was created and nothing happened. On the side bar it merely complained

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Code Reviewer
There was an issue with reviewing this pull request

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There is no other information provided to explain what went wrong? How to troubleshoot such events?

[Jovana Dunisijevic]

Hey @aaron_seet 

When you see that error and no further details are provided, it can be frustrating to troubleshoot. I am sorry about that!

Let me see if I can help you diagnose the issue:

1. Large Pull Request Diffs

• Bitbucket and code review tools have limits on the size of diffs they can process. If your pull request contains a very large number of changes (lines/files), the Code Reviewer may fail to analyse it.

• How to check:

  • Clone your repository locally.

  • For unmerged PRs, run:

    git diff <sourceBranchCommit>...<targetBranchCommit> --shortstat

  • For merged PRs, run:

    git diff <parentCommit1>...<parentCommit2> --shortstat

  • If the diff is very large, try splitting your changes into smaller PRs and see if the Code Reviewer works on those

2. Browser or Extension Issues

• Sometimes, browser extensions (like ad blockers or privacy tools) can interfere with pull request features.

• How to check:

  • Try opening the PR in an incognito/private window.

  • Disable browser extensions one by one to see if the issue resolves.

  • Try a different browser

3. Temporary Service Issues or Bugs

• Occasionally, backend issues or outages can cause the Code Reviewer to fail. If the problem is intermittent or affects all PRs, check Atlassian’s status page or community for ongoing incidents.

• If the issue persists across multiple PRs and users, it may be a bug or a temporary backend problem

4. Other Troubleshooting Steps

• Check permissions: Make sure the Code Reviewer app/bot has access to the repository and the PR.

• Check PR settings: Ensure the PR is not a draft, and all required fields are filled.

• Try a different PR: See if the Code Reviewer works on a different, smaller PR to isolate the problem.

5. If All Else Fails

• If none of the above steps help, gather as much information as possible (PR size, browser, error screenshots, logs if available) and raise a support ticket with Atlassian. Include the exact error message and steps to reproduce

For more details, see Atlassian’s official troubleshooting guide: https://support.atlassian.com/bitbucket-cloud/kb/something-went-wrong-error-message-when-attempting-to-review-a-pull-request/

Let me know if this helps you at all!

Kindest regards,

Jovana

[aaron_seet]

Is this really a lot?

git diff 024e12deffb5973f84c85a0376b64ce6f9de5f78...be0d78a9fe7e140ba3a15d2d0b93861583ce8686 --shortstat
52 files changed, 12643 insertions(+), 267 deletions(-)

[Jovana Dunisijevic]

Hey @aaron_seet 

Thank you for sharing the stats on your PR!

Actually, 52 files changed with 12,643 insertions and 267 deletions is considered a large pull request (PR) for most code review tools, including Atlassian's Code Reviewer and Bitbucket.

Large PRs like this could cause some issues:

• Performance problems: The UI may time out or fail to load the diff, especially if there are many files or a high number of insertions. Atlassian documentation and community threads mention that very large commits (e.g., thousands of files or hundreds of thousands of insertions) can cause the PR page to fail to load or display errors: https://support.atlassian.com/bitbucket-cloud/kb/how-to-identify-large-files-in-a-commit/

• Webhook and automation failures: Bitbucket webhooks, which trigger pipelines and other automations, have a payload size limit (256 KB). Large PRs can exceed this, causing pipelines or integrations not to trigger

• Review quality and process: Best practices recommend keeping PRs small and focused to make reviews more effective and less error-prone. Large PRs are harder to review thoroughly, increasing the risk of missed bugs or regressions

Some guidance:

• Many teams try to keep PRs under 10-20 files and a few hundred lines of changes.

• PRs with more than 1,000 insertions or dozens of files are often flagged as "too large" and may be split up for easier review.

• Atlassian's own support articles and community posts confirm that PRs with thousands of insertions or many files can cause technical and process issues

In summary, your PR is on the high end of what most code review tools and processes can handle smoothly. If possible, try to break it into smaller, more manageable PRs. If that's not feasible, reviewers should be prepared for potential UI slowdowns or errors, and you may need to use command-line tools to review or troubleshoot the PR if the web UI fails.

Let me know where else I can help you!

Kindest regards,

Jovana

[aaron_seet]

The reality is well over new 11K lines were Entity Framework database migration code. It's a one-time independent file and not part of regular application code base. The regular files changed a few to dozens of lines.