microsoft/playwright-mcp · error · Error

Markers for generated section not found in README

Error message

Markers for generated section not found in README

What it means

update-readme.js regenerates README sections by locating HTML comment markers (`<!--- ... generated by ... -->` and `<!--- End of ... generated section -->`) inside README.md and splicing new content between them. `updateSection` throws this error when either the start or end marker string cannot be found via `indexOf`, meaning the README no longer contains intact, well-formed markers. It exists as a fail-fast guard so the script never silently appends duplicate sections or clobbers the wrong part of the doc.

Solutions

1. Restore both markers in README.md exactly as the script defines them: check the `startMarker`/`endMarker` template strings in update-readme.js (e.g. `<!--- Tools generated by update-readme.js -->` and `<!--- End of tools generated section -->`) and ensure each appears verbatim, in order, in the README.
2. If markers were lost, `git checkout HEAD -- README.md` (or copy them from an older tag) to recover the marker lines, then rerun the script.
3. Never hand-edit content between the markers; place custom prose outside the generated sections so formatters and edits don't disturb the markers.

Example fix

# before (README.md) — end marker corrupted
<!--- Tools generated by update-readme.js -->
...old table...
<!---End of tools generated section--->

# after
<!--- Tools generated by update-readme.js -->
...old table...
<!--- End of tools generated section -->

// Verify markers exist before invoking the generator:
import fs from 'fs';

const readme = fs.readFileSync('README.md', 'utf-8');
const markers = [
  '<!--- Tools generated by update-readme.js -->',
  '<!--- End of tools generated section -->',
  '<!--- Config generated by update-readme.js -->',
  '<!--- End of config generated section -->',
];
const missing = markers.filter(m => !readme.includes(m));
if (missing.length) {
  console.error('README markers missing:', missing);
  process.exit(1);
}

function hasGeneratedMarkers(readme, startMarker, endMarker) {
  const s = readme.indexOf(startMarker);
  const e = readme.indexOf(endMarker);
  return s !== -1 && e !== -1 && s < e;
}

try {
  await updateReadme();
} catch (e) {
  if (/Markers for generated section not found/.test(e.message)) {
    // restore markers from git rather than letting the script rewrite the README
    execSync('git checkout HEAD -- README.md');
    throw new Error('README markers were corrupted; restored from git. Re-apply manual edits outside generated sections.');
  }
  throw e;
}

When it happens

Trigger: Running `node utils/update-readme.js` when README.md is missing a marker comment, has a typo in one (e.g. `<!---End of tools generated section -->` missing a space, or `--->`), has the markers reordered (end before start), or when a hand-edit accidentally deleted a marker line. Also triggered by tools that reformat/lint markdown and alter or strip the HTML comments.

Common situations: Manual edits to README.md that touch the generated sections; a merge conflict resolution that drops marker lines; Prettier/markdown formatters normalizing comment syntax; partial reverts where only one of the paired markers was removed.

Related errors

• Config type not found in config.d.ts
• Unknown tool capabilities

AI-assisted analysis of microsoft/playwright-mcp@16cf228d7b (2026-08-27). Data as JSON: /api/errors/155bc8972b647ae4. Report an issue: GitHub.

Appendix: source

Thrown at update-readme.js:109

    lines.push(`  - Parameters: None`);
  }
  lines.push(`  - Read-only: **${tool.type === 'readOnly'}**`);
  lines.push('');
  return lines;
}

/**
 * @param {string} content
 * @param {string} startMarker
 * @param {string} endMarker
 * @param {string[]} generatedLines
 * @returns {Promise<string>}
 */
async function updateSection(content, startMarker, endMarker, generatedLines) {
  const startMarkerIndex = content.indexOf(startMarker);
  const endMarkerIndex = content.indexOf(endMarker);
  if (startMarkerIndex === -1 || endMarkerIndex === -1)
    throw new Error('Markers for generated section not found in README');

  return [
    content.slice(0, startMarkerIndex + startMarker.length),
    '',
    generatedLines.join('\n'),
    '',
    content.slice(endMarkerIndex),
  ].join('\n');
}

/**
 * @param {string} content
 * @returns {Promise<string>}
 */
async function updateTools(content) {
  console.log('Loading tool information from compiled modules...');

  const generatedLines = /** @type {string[]} */ ([]);

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