phacility/phabricator · error · Exception

Changeset ID "%s" is part of diff ID "%s", but that diff is

Error message

Changeset ID "%s" is part of diff ID "%s", but that diff is attached to revision "%s", not revision "%s".

What it means

Even when the revision and the changeset both exist, the controller verifies they belong together: the changeset's diff must be attached to the same revision. A mismatch throws this error. The check protects against stale parameter mixing and cross-revision request construction.

Source

Thrown at src/applications/differential/controller/DifferentialInlineCommentEditController.php:54

    $changeset_id = $this->getChangesetID();
    $viewer = $this->getViewer();

    $revision = $this->loadRevision();

    $changeset = id(new DifferentialChangesetQuery())
      ->setViewer($viewer)
      ->withIDs(array($changeset_id))
      ->executeOne();
    if (!$changeset) {
      throw new Exception(
        pht(
          'Invalid changeset ID "%s"!',
          $changeset_id));
    }

    $diff = $changeset->getDiff();
    if ($diff->getRevisionID() != $revision->getID()) {
      throw new Exception(
        pht(
          'Changeset ID "%s" is part of diff ID "%s", but that diff '.
          'is attached to revision "%s", not revision "%s".',
          $changeset_id,
          $diff->getID(),
          $diff->getRevisionID(),
          $revision->getID()));
    }

    return id(new DifferentialInlineComment())
      ->setRevision($revision)
      ->setChangesetID($changeset_id);
  }

  protected function loadCommentForDone($id) {
    $viewer = $this->getViewer();

    $inline = $this->loadCommentByID($id);

View on GitHub (pinned to 5720a38cfe)

Solutions

Always derive both the revision id and the changeset id from the same revision/diff view.
Re-render the comment form after the revision updates, so it embeds current IDs.
In automation, fetch the changesets of the specific revision and use only those IDs.

Defensive patterns

Strategy: validation

Validate before calling

// before posting an inline comment, confirm the changeset id belongs to the
// revision being commented on
$changeset_ids = array(); // ids rendered with the current diff view
if (!in_array($changeset_id, $changeset_ids, true)) {
  throw new InvalidArgumentException(
    'Changeset does not belong to this revision.');
}

Try / catch

try {
  // submit the inline comment
} catch (Exception $ex) {
  if (preg_match('/is part of diff ID/', $ex->getMessage())) {
    // mixed ids: refresh both from the same revision view and resubmit
  } else {
    throw $ex;
  }
}

Prevention

Derive the revision id and the changeset id from the same diff view.
Re-render comment forms after revision updates so embedded ids stay current.
Do not reuse captured changeset ids across revisions.

When it happens

Trigger: Mixing a changeset id from revision A with the revision id of revision B in one inline-comment request — stale forms, request replay, or hand-built parameters.

Common situations: Two revisions open in parallel with a copy-pasted URL; automation that caches changeset IDs and reuses them across revisions.

Related errors

AI-assisted analysis of phacility/phabricator@5720a38cfe (2026-08-21). Data as JSON: /api/errors/cc821a1a76032bf0. Report an issue: GitHub.