phacility/phabricator · warning · PhabricatorSearchConstraintException

Mercurial does not currently support searching for ancestors

Error message

Mercurial does not currently support searching for ancestors of a particular ref.

What it means

The same ancestors-of-refs constraint applied to a Mercurial repository: unlike SVN it is conceptually possible, but Phabricator's implementation ('does not currently support') does not cover it, so the search is blocked with PhabricatorSearchConstraintException.

Source

Thrown at src/applications/diffusion/query/DiffusionCommitQuery.php:583

      $repository = id(new PhabricatorRepositoryQuery())
        ->setViewer($viewer)
        ->withIDs(array($repository_id))
        ->executeOne();

      if (!$repository) {
        throw new PhabricatorEmptyQueryException();
      }

      if ($repository->isSVN()) {
        throw new PhabricatorSearchConstraintException(
          pht(
            'Subversion does not support searching for ancestors of '.
            'a particular ref. This operation is not meaningful in '.
            'Subversion.'));
      }

      if ($repository->isHg()) {
        throw new PhabricatorSearchConstraintException(
          pht(
            'Mercurial does not currently support searching for ancestors of '.
            'a particular ref.'));
      }

      $can_constrain = true;
      $history_identifiers = array();
      foreach ($this->ancestorsOf as $key => $ref) {
        try {
          $raw_history = DiffusionQuery::callConduitWithDiffusionRequest(
            $viewer,
            DiffusionRequest::newFromDictionary(
              array(
                'repository' => $repository,
                'user' => $viewer,
              )),
            'diffusion.historyquery',
            array(

View on GitHub (pinned to 5720a38cfe)

Solutions

1. Drop the ancestors-of filter for Mercurial repositories and use paths, authors, or date constraints instead
2. Track the upstream feature request; support may arrive in a newer Phabricator release, so retest after upgrades
3. Branch shared query code on repository VCS before applying ancestor constraints

if ($repository->isHg()) {
  // hide or reject the ancestors-of filter until support ships
}

function supportsAncestorSearch(PhabricatorRepository $repository) {
  return !$repository->isSVN() && !$repository->isHg();
}

try {
  $results = $query->execute();
} catch (PhabricatorSearchConstraintException $ex) {
  // explain the feature is git-only today; suggest path/author/date constraints
}

When it happens

Trigger: A commit search includes ancestorsOf, constrained to exactly one repository, and that repository is Mercurial.

Common situations: Teams migrating git-based workflows or dashboards to Mercurial repositories and expecting identical ancestor filters; shared API code that worked against git.

Related errors

• Subversion does not support searching for ancestors of a par
• Password providers can't be linked.
• Mercurial command appears to contain unsafe injected "--conf
• Unknown Mercurial command "%s"!
• To search for commits which are ancestors of particular refs

AI-assisted analysis of phacility/phabricator@5720a38cfe (2026-08-21). Data as JSON: /api/errors/cb52daffab575cce. Report an issue: GitHub.