phacility/phabricator · error · Exception

This is not a valid JSON document and can not be rendered as

Error message

This is not a valid JSON document and can not be rendered as a Jupyter notebook: %s.

What it means

PhabricatorJupyterDocumentEngine::newCells() first parses the notebook with phutil_json_decode(); a PhutilJSONParserException means the file is not syntactically valid JSON at all, so it can never be a Jupyter notebook. The message includes the parser's detail (syntax error and position).

Source

Thrown at src/applications/files/document/PhabricatorJupyterDocumentEngine.php:311

        'class' => 'jupyter-notebook',
      ),
      $rows);

    $container = phutil_tag(
      'div',
      array(
        'class' => 'document-engine-jupyter',
      ),
      $notebook_table);

    return $container;
  }

  private function newCells($content, $for_diff) {
    try {
      $data = phutil_json_decode($content);
    } catch (PhutilJSONParserException $ex) {
      throw new Exception(
        pht(
          'This is not a valid JSON document and can not be rendered as '.
          'a Jupyter notebook: %s.',
          $ex->getMessage()));
    }

    if (!is_array($data)) {
      throw new Exception(
        pht(
          'This document does not encode a valid JSON object and can not '.
          'be rendered as a Jupyter notebook.'));
    }

    $nbformat = idx($data, 'nbformat');
    if ($nbformat == null || !strlen($nbformat)) {
      throw new Exception(
        pht(
          'This document is missing an "nbformat" field. Jupyter notebooks '.

View on GitHub (pinned to 5720a38cfe)

Solutions

1. Validate locally to find the exact syntax error: python -m json.tool file.ipynb
2. Re-export the notebook from Jupyter (File > Save/Export) or re-download it and upload the fresh copy
3. Fix the JSON defect directly (truncation, trailing commas, conflict markers) and re-upload

$data = json_decode($raw, true);
if ($data === null && json_last_error() !== JSON_ERROR_NONE) {
  // invalid JSON: reject before sending to the Jupyter engine
}

catch Exception from the notebook renderer and show the embedded parser message — it pinpoints the JSON syntax error position.

When it happens

Trigger: Uploading a file treated as a notebook whose body is malformed JSON: truncated download, an HTML error page saved with a .ipynb extension, hand-edited JSON with a trailing comma, or merge-conflict markers left inside the file.

Common situations: Notebooks truncated during transfer or git conflicts resolved poorly; files saved from a browser preview instead of downloaded; notebooks corrupted by line-ending or encoding mangles.

Related errors

• This document does not encode a valid JSON object and can no
• This Jupyter notebook does not specify any notebook cells.
• Keyring configuration is not valid: value must be a list of
• Keyring configuration is not valid: each entry in the list m
• Keyring configuration has an invalid key specification (at i

AI-assisted analysis of phacility/phabricator@5720a38cfe (2026-08-21). Data as JSON: /api/errors/4bdd740020fddb85. Report an issue: GitHub.