dotnet/efcore · error · Exception

Failed to download , Status Code

Error message

Failed to download {url}, Status Code: {response.status}

What it means

Raised by download_file when the HTTP response status is anything other than 200. Like the SHA256 case it is a bare Exception, so it escapes the retry except clause and fails immediately: a 404/403/500 is NOT retried despite the retry loop.

Solutions

  1. Open {mirror}/{filename} in a browser or curl -I it to see the real status code and body.
  2. Confirm --mirror, --suite, and --arch form a valid combination (e.g. the arch exists for that suite).
  3. Try a different, official mirror.
  4. If the status is 5xx, wait and re-run the whole pipeline later.
  5. Check HTTP_PROXY/HTTPS_PROXY env vars are not routing to a broken proxy.

Example fix

// before
else:
    raise Exception(f"Failed to download {url}, Status Code: {response.status}")  # not retried

// after
else:
    # raise a type the except clause covers so the retry loop actually engages
    raise aiohttp.ClientError(f"HTTP {response.status} for {url}")
Defensive patterns

Strategy: retry

Validate before calling

# preflight: HEAD one package URL to confirm the mirror serves it before the full run
import aiohttp
async def head_ok(mirror, filename):
    async with aiohttp.ClientSession() as s:
        async with s.get(f"{mirror}/{filename}") as r:
            return r.status == 200
# if not asyncio.run(head_ok(args.mirror, sample_filename)): sys.exit('mirror cannot serve debs')

Try / catch

try:
    asyncio.run(download_deb_files_parallel(mirror, packages, tmp_dir))
except Exception as e:
    if "Status Code" in str(e):
        raise SystemExit(f"mirror returned non-200, check mirror/suite/arch: {e}")
    raise

Prevention

When it happens

Trigger: session.get(url) returns a non-200 status for a .deb URL built as {mirror}/{info['Filename']}. Typical when the Packages index references a file path the mirror does not actually serve.

Common situations: --suite/--arch/--mirror mismatch (index from one suite, files from another), package removed from the suite, mirror temporarily returning 5xx, arch not published on that mirror, or a redirect to an HTML error page that aiohttp did not follow.

Related errors

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/437087a09524af21. Report an issue: GitHub.

Appendix: source

Thrown at eng/common/cross/install-debs.py:40

    attempt = 0
    while attempt < max_retries:
        try:
            async with session.get(url, timeout=aiohttp.ClientTimeout(total=timeout)) as response:
                if response.status == 200:
                    with open(dest_path, "wb") as f:
                        content = await response.read()

                        # verify checksum if provided
                        if checksum:
                            sha256 = hashlib.sha256(content).hexdigest()
                            if sha256 != checksum:
                                raise Exception(f"SHA256 mismatch for {url}: expected {checksum}, got {sha256}")

                        f.write(content)
                    print(f"Downloaded {url} at {dest_path}")
                    return
                else:
                    raise Exception(f"Failed to download {url}, Status Code: {response.status}")
        except (asyncio.CancelledError, asyncio.TimeoutError, aiohttp.ClientError) as e:
            print(f"Error downloading {url}: {type(e).__name__} - {e}. Retrying...")

        attempt += 1
        await asyncio.sleep(retry_delay)

    raise Exception(f"Failed to download {url} after {max_retries} attempts.")

async def download_deb_files_parallel(mirror, packages, tmp_dir):
    """Download .deb files in parallel."""
    os.makedirs(tmp_dir, exist_ok=True)

    tasks = []
    timeout = aiohttp.ClientTimeout(total=60)
    async with aiohttp.ClientSession(timeout=timeout) as session:
        for pkg, info in packages.items():
            filename = info.get("Filename")
            if filename:

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