unclecode/crawl4ai · error · ValueError

Process HTML, Failed to extract content from the website: {u

Error message

Process HTML, Failed to extract content from the website: {url}, error: {str(e)}

What it means

The catch-all handler in aprocess_html: any exception raised inside the scraping/processing block (other than InvalidCSSSelectorError, which is re-raised verbatim) is wrapped in this ValueError with the original message appended. The root cause is in {str(e)}; this wrapper only adds the failing URL context.

Source

Thrown at crawl4ai/async_webcrawler.py:794

            # add keys from kwargs to params that doesn't exist in params
            params.update({k: v for k, v in kwargs.items()
                          if k not in params.keys()})

            ################################
            # Scraping Strategy Execution  #
            ################################
            result: ScrapingResult = scraping_strategy.scrap(
                url, html, **params)

            if result is None:
                raise ValueError(
                    f"Process HTML, Failed to extract content from the website: {url}"
                )

        except InvalidCSSSelectorError as e:
            raise ValueError(str(e))
        except Exception as e:
            raise ValueError(
                f"Process HTML, Failed to extract content from the website: {url}, error: {str(e)}"
            )

        # Extract results - handle both dict and ScrapingResult
        if isinstance(result, dict):
            cleaned_html = sanitize_input_encode(
                result.get("cleaned_html", ""))
            media = result.get("media", {})
            tables = media.pop("tables", []) if isinstance(media, dict) else []
            links = result.get("links", {})
            metadata = result.get("metadata", {})
        else:
            cleaned_html = sanitize_input_encode(result.cleaned_html)
            # media = result.media.model_dump()
            # tables = media.pop("tables", [])
            # links = result.links.model_dump()
            media = result.media.model_dump() if hasattr(result.media, 'model_dump') else result.media
            tables = media.pop("tables", []) if isinstance(media, dict) else []

View on GitHub (pinned to 7e80152142)

Solutions

Read the trailing 'error: ...' part of the message — it contains the true exception; fix that root cause.
For InvalidCSSSelectorError text, fix the css_selector syntax in CrawlerRunConfig (e.g. unbalanced quotes, unsupported pseudo-selectors).
Validate/re-serialize the input HTML before passing html= (parse it with BeautifulSoup and re-encode).
If an extraction strategy fails, check its config/API keys or set config.extraction_strategy to None to isolate.

Example fix

# before
result = await crawler.arun(url, html=html, config=CrawlerRunConfig(css_selector="a[href='"))

# after
result = await crawler.arun(url, html=html, config=CrawlerRunConfig(css_selector="a[href]"))

Defensive patterns

Strategy: try-catch

Validate before calling

from bs4 import BeautifulSoup
def is_parseable_html(html: str) -> bool:
    try:
        BeautifulSoup(html, 'lxml')
        return True
    except Exception:
        return False

Try / catch

try:
    result = await crawler.arun(url, html=html, config=config)
except ValueError as e:
    msg = str(e)
    if 'error:' in msg:
        root = msg.split('error:', 1)[1].strip()
        logger.warning('scrape failed for %s: %s', url, root)
    else:
        raise

Prevention

Log the 'error:' suffix — it holds the root cause, the wrapper does not.
Test css_selector values with a CSS parser before use.
Keep extraction strategies isolated so you can disable them to bisect failures.

When it happens

Trigger: Exceptions thrown by the content scraping pipeline: malformed input HTML crashing BeautifulSoup/lxml, broken extraction strategies (LLM API errors inside an ExtractionStrategy invoked via params), errors in html2text conversion, or bugs in user-supplied scrap hooks. InvalidCSSSelectorError from bad css_selector is raised separately as its own message.

Common situations: Passing invalid CSS selectors (those surface as InvalidCSSSelectorError text); corrupted or truncated saved HTML; extraction strategies requiring API keys that are missing; version mismatches in html2text/lxml after upgrades.

Related errors

AI-assisted analysis of unclecode/crawl4ai@7e80152142 (2026-08-14). Data as JSON: /api/errors/4e7fd69b6f45fe12. Report an issue: GitHub.