SeleniumHQ/selenium · error · ValueError

Fetch failed (HTTP {response.status}): {url}

Error message

Fetch failed (HTTP {response.status}): {url}

What it means

Raised by fetch_and_save() in scripts/update_cdp.py when an HTTP GET to a URL returns non-200. This function downloads Chrome DevTools Protocol (CDP) .pdl files and saves them to disk. It is called from add_pdls() to download browser_protocol.pdl and js_protocol.pdl from the chromium/chromium and v8/v8 repositories on GitHub.

Source

Thrown at scripts/update_cdp.py:48

        "https://googlechromelabs.github.io/chrome-for-testing/last-known-good-versions.json",
    )
    milestone = json.loads(r.data)["channels"][channel]["version"].split(".")[0]
    r = http.request(
        "GET",
        "https://googlechromelabs.github.io/chrome-for-testing/known-good-versions-with-downloads.json",
    )
    versions = json.loads(r.data)["versions"]

    return sorted(
        filter(lambda v: v["version"].split(".")[0] == str(milestone), versions),
        key=lambda v: parse(v["version"]),
    )[-1]


def fetch_and_save(url, file_path):
    response = http.request("GET", url)
    if response.status != 200:
        raise ValueError(f"Fetch failed (HTTP {response.status}): {url}")
    with open(file_path, "wb") as file:
        file.write(response.data)


def new_chrome(chrome_milestone):
    return chrome_milestone["version"].split(".")[0]


def previous_chrome(chrome_milestone):
    return str(int(new_chrome(chrome_milestone)) - 1)


def old_chrome(chrome_milestone):
    return str(int(new_chrome(chrome_milestone)) - 3)


def flatten_browser_pdl(file_path, chrome_version):
    """Preserves the version block and concatenates all included domain .pdl files."""

View on GitHub (pinned to aa36b38e69)

Solutions

1. Retry the script — raw.githubusercontent.com failures are often transient.
2. Verify the specific URL from the error message is accessible (curl -I).
3. Check if the Chromium devtools protocol directory structure changed and update the URL pattern in update_cdp.py if so.
4. Manually verify the Chrome version tag exists in the chromium/chromium repo.

Example fix

null

import urllib3
http = urllib3.PoolManager()
r = http.request('HEAD', url)
if r.status != 200:
    print(f'CDP file not available at {url}, deferring update_cdp')

null

try:
    fetch_and_save(url, file_path)
except ValueError as e:
    print(f'Failed to fetch CDP file: {e}')
    # retry or report

When it happens

Trigger: Running update_cdp.py when a CDP .pdl file URL returns non-200: the file was moved/renamed in the Chromium repo (404), the Chrome version tag does not exist, GitHub raw content is temporarily unavailable, or network issues. The URLs point to raw.githubusercontent.com/chromium/chromium/{version}/...

Common situations: Chromium repo reorganization moving .pdl files; the Chrome version string in the JSON does not correspond to a valid git tag; transient GitHub CDN failure; network proxy blocking raw.githubusercontent.com; the v8_revision in DEPS points to a commit where js_protocol.pdl was at a different path.

Related errors

• Download unavailable (HTTP {r.status}): {url}
• Failed to download {url}: HTTP {r.status}
• No v8_revision found in DEPS for Chrome {chrome_milestone['v
• Failed to list {CDDL_PATH} at {commit}: HTTP {r.status}
• Failed to resolve {repo}@{branch}: HTTP {r.status}

AI-assisted analysis of SeleniumHQ/selenium@aa36b38e69 (2026-08-14). Data as JSON: /api/errors/ad669762a64952a9. Report an issue: GitHub.