Firecrawl advanced troubleshooting

Firecrawl Advanced Troubleshooting

Overview

Deep debugging techniques for complex Firecrawl issues: empty scrapes on certain domains, crawl jobs that never complete, inconsistent extraction results, and webhook delivery failures. Uses systematic layer-by-layer isolation.

Instructions

Step 1: Minimal Reproduction

import FirecrawlApp from "@mendable/firecrawl-js";

// Strip everything down to the simplest failing case
async function minimalRepro() {
  const firecrawl = new FirecrawlApp({
    apiKey: process.env.FIRECRAWL_API_KEY!,
  });

  // Test 1: Can we scrape at all?
  console.log("Test 1: Basic scrape");
  const basic = await firecrawl.scrapeUrl("https://example.com", {
    formats: ["markdown"],
  });
  console.log(`  Success: ${basic.success}, Length: ${basic.markdown?.length}`);

  // Test 2: Does the target URL work?
  console.log("Test 2: Target URL");
  const target = await firecrawl.scrapeUrl("https://YOUR-FAILING-URL.com", {
    formats: ["markdown"],
  });
  console.log(`  Success: ${target.success}, Length: ${target.markdown?.length}`);

  // Test 3: With waitFor for JS rendering
  console.log("Test 3: With JS wait");
  const withWait = await firecrawl.scrapeUrl("https://YOUR-FAILING-URL.com", {
    formats: ["markdown"],
    waitFor: 10000,
    onlyMainContent: true,
  });
  console.log(`  Success: ${withWait.success}, Length: ${withWait.markdown?.length}`);

  // Test 4: With actions
  console.log("Test 4: With actions");
  const withActions = await firecrawl.scrapeUrl("https://YOUR-FAILING-URL.com", {
    formats: ["markdown", "screenshot"],
    actions: [
      { type: "wait", milliseconds: 3000 },
      { type: "scroll", direction: "down" },
      { type: "wait", milliseconds: 2000 },
    ],
  });
  console.log(`  Success: ${withActions.success}, Length: ${withActions.markdown?.length}`);
  // Screenshot will show what Firecrawl actually sees
}

Step 2: Layer-by-Layer Isolation

async function diagnose(url: string) {
  const firecrawl = new FirecrawlApp({ apiKey: process.env.FIRECRAWL_API_KEY! });
  const results: Array<{ test: string; pass: boolean; detail: string }> = [];

  // Layer 1: API connectivity
  try {
    await firecrawl.scrapeUrl("https://example.com", { formats: ["markdown"] });
    results.push({ test: "API connectivity", pass: true, detail: "OK" });
  } catch (e: any) {
    results.push({ test: "API connectivity", pass: false, detail: `${e.statusCode}: ${e.message}` });
    return results; // can't continue
  }

  // Layer 2: Target URL accessibility
  try {
    const result = await firecrawl.scrapeUrl(url, { formats: ["markdown"] });
    const hasContent = (result.markdown?.length || 0) > 50;
    results.push({
      test: "Target scrape",
      pass: result.success && hasContent,
      detail: `Success: ${result.success}, Chars: ${result.markdown?.length}, Status: ${result.metadata?.statusCode}`,
    });
  } catch (e: any) {
    results.push({ test: "Target scrape", pass: false, detail: e.message });
  }

  // Layer 3: Content quality
  try {
    const result = await firecrawl.scrapeUrl(url, {
      formats: ["markdown", "html"],
      onlyMainContent: true,
      waitFor: 5000,
    });
    const md = result.markdown || "";
    const isErrorPage = /404|403|access denied|captcha|blocked/i.test(md);
    results.push({
      test: "Content quality",
      pass: md.length > 100 && !isErrorPage,
      detail: `Chars: ${md.length}, Error page: ${isErrorPage}, Has headings: ${/^#{1,3}\s/m.test(md)}`,
    });
  } catch (e: any) {
    results.push({ test: "Content quality", pass: false, detail: e.message });
  }

  // Layer 4: Map endpoint (URL discovery)
  try {
    const map = await firecrawl.mapUrl(url);
    results.push({
      test: "Map endpoint",
      pass: (map.links?.length || 0) > 0,
      detail: `Found ${map.links?.length} URLs`,
    });
  } catch (e: any) {
    results.push({ test: "Map endpoint", pass: false, detail: e.message });
  }

  return results;
}

// Run diagnosis
const results = await diagnose("https://YOUR-URL.com");
console.table(results);

Step 3: Debug Empty Scrapes

// When scrapeUrl returns empty or thin markdown:
async function debugEmptyScrape(url: string) {
  const firecrawl = new FirecrawlApp({ apiKey: process.env.FIRECRAWL_API_KEY! });

  // Get all formats to understand what Firecrawl sees
  const result = await firecrawl.scrapeUrl(url, {
    formats: ["markdown", "html", "screenshot"],
    waitFor: 10000,
  });

  console.log("=== Scrape Debug ===");
  console.log(`URL: ${result.metadata?.sourceURL}`);
  console.log(`Status: ${result.metadata?.statusCode}`);
  console.log(`Markdown length: ${result.markdown?.length || 0}`);
  console.log(`HTML length: ${result.html?.length || 0}`);
  console.log(`Title: ${result.metadata?.title}`);

  // Check if HTML has content but markdown doesn't
  if ((result.html?.length || 0) > 1000 && (result.markdown?.length || 0) < 100) {
    console.log("DIAGNOSIS: HTML has content but markdown extraction failed");
    console.log("FIX: Content may be in iframes or shadow DOM. Try with actions.");
  }

  // Check for bot detection
  if (/captcha|cloudflare|access denied|please verify/i.test(result.html || "")) {
    console.log("DIAGNOSIS: Bot detection / CAPTCHA detected");
    console.log("FIX: Site blocks automated scraping. Contact Firecrawl support.");
  }

  return result;
}

Step 4: Debug Stuck Crawl Jobs

async function debugCrawlJob(jobId: string) {
  const firecrawl = new FirecrawlApp({ apiKey: process.env.FIRECRAWL_API_KEY! });

  const status = await firecrawl.checkCrawlStatus(jobId);
  console.log("=== Crawl Job Debug ===");
  console.log(`Status: ${status.status}`);
  console.log(`Completed: ${status.completed}/${status.total}`);
  console.log(`Error: ${status.error || "none"}`);

  if (status.status === "scraping" && status.completed === status.total) {
    console.log("DIAGNOSIS: All pages scraped but job not marked complete");
    console.log("FIX: This is a Firecrawl backend issue. Wait or start a new crawl.");
  }

  if (status.completed === 0 && status.status === "scraping") {
    console.log("DIAGNOSIS: Crawl started but no pages scraped");
    console.log("FIX: Check if start URL returns content. Try scrapeUrl first.");
  }
}

Step 5: Timing Analysis

async function timeScrape(url: string, iterations = 5) {
  const firecrawl = new FirecrawlApp({ apiKey: process.env.FIRECRAWL_API_KEY! });
  const times: number[] = [];

  for (let i = 0; i < iterations; i++) {
    const start = Date.now();
    await firecrawl.scrapeUrl(url, { formats: ["markdown"] });
    times.push(Date.now() - start);
  }

  times.sort((a, b) => a - b);
  console.log(`p50: ${times[Math.floor(times.length * 0.5)]}ms`);
  console.log(`p95: ${times[Math.floor(times.length * 0.95)]}ms`);
  console.log(`min: ${times[0]}ms, max: ${times[times.length - 1]}ms`);
}

Error Handling

Issue	Cause	Solution
Empty markdown, HTML exists	Shadow DOM or iframes	Use actions to interact with page
Scrape returns CAPTCHA	Bot detection	Try with mobile: true, contact Firecrawl
Crawl stuck at 0 pages	Start URL blocked	Verify URL loads in browser first
Inconsistent results	JS rendering timing	Increase waitFor, use selector-based wait
Webhook never fires	URL unreachable	Test with curl to your endpoint first

Support Escalation Template

Subject: [P1/P2/P3] [Brief description]

URL: [failing URL]
API Key prefix: fc-xxx (first 6 chars)
Timestamp: [ISO 8601]

Expected: [what should happen]
Actual: [what happens]

Diagnostic output: [paste from diagnose() above]
Screenshot: [if available from screenshot format]

Workarounds tried:
1. [what you tried] — result: [outcome]

Resources

• Firecrawl Advanced Scraping
• GitHub Issues
• Firecrawl Discord

Next Steps

For load testing, see firecrawl-load-scale.