Cloudflare API Timeout: Fix Error 524, 522, and RequestTimeout Errors

Understanding Cloudflare API Timeout Errors

The phrase "Cloudflare API timeout" covers two distinct failure modes that engineers conflate:

1. Your users hit your origin through Cloudflare and receive a 5xx timeout error page served by Cloudflare.
2. Your automation hits api.cloudflare.com (Cloudflare's own management API) and receives a timeout response.

Both require different diagnosis paths. This guide covers both.

Error Taxonomy

The presence of the CF-RAY response header tells you whether Cloudflare proxied the request (your origin) or the error originated from Cloudflare's API platform itself.

Step 1: Identify Which Timeout You Have

Run the following curl to capture headers:

curl -svo /dev/null https://yourdomain.com/your-slow-endpoint 2>&1 | grep -E 'CF-RAY|< HTTP|cf-cache'

If you see CF-RAY: in the output, Cloudflare proxied the request and the timeout is between Cloudflare and your origin.

For api.cloudflare.com errors, add -w "%{http_code}" to your API calls:

curl -s -o /dev/null -w "%{http_code}" \
  -H "Authorization: Bearer $CF_API_TOKEN" \
  "https://api.cloudflare.com/client/v4/zones"

A 504 or 408 from api.cloudflare.com warrants checking https://www.cloudflarestatus.com before any local debugging.

Step 2: Diagnose Error 524 (Origin Too Slow)

Error 524 fires when your origin holds the connection open but never completes an HTTP response. Common triggers:

• Database queries without proper indexes on large tables
• Synchronous file processing (PDF generation, image resizing) on the web thread
• External HTTP calls from your origin with no timeout set
• PHP/Python scripts that flush() no output until completion

Measure your actual origin response time bypassing Cloudflare:

# Replace 1.2.3.4 with your real origin IP
curl -o /dev/null -w "\nTime: %{time_total}s\nHTTP: %{http_code}\n" \
  --resolve yourdomain.com:443:1.2.3.4 \
  https://yourdomain.com/your-slow-endpoint

If time_total exceeds 100 seconds you will always get 524 on standard Cloudflare plans.

Nginx origin — increase upstream timeout:

location /your-slow-endpoint {
    proxy_read_timeout 300s;
    proxy_connect_timeout 10s;
    proxy_send_timeout 300s;
    proxy_pass http://upstream_backend;
}

Note: Increasing proxy_read_timeout on your origin server does not change Cloudflare's 100-second gateway limit on Free/Pro/Business plans. Enterprise plans can request a longer timeout from Cloudflare support. The correct long-term fix is making the endpoint respond faster or going async.

Check what Cloudflare's edge sees via diagnostic headers:

curl -I -H "CF-Debug: 1" https://yourdomain.com/your-slow-endpoint 2>&1 | head -30

Step 3: Diagnose Error 522 (TCP Connection Failed)

Error 522 fires when Cloudflare cannot complete a TCP handshake to your origin's IP within 15 seconds. The three most common causes:

1. Origin firewall blocking Cloudflare IPs — the #1 cause
2. Origin server process not listening on the expected port
3. Network route instability between Cloudflare's edge and your origin datacenter

Verify Cloudflare IPs are whitelisted:

# Download current Cloudflare IPv4 ranges
curl -s https://www.cloudflare.com/ips-v4 -o /tmp/cf-ips-v4.txt
curl -s https://www.cloudflare.com/ips-v6 -o /tmp/cf-ips-v6.txt

# Check if iptables is blocking them (Linux)
sudo iptables -L INPUT -n --line-numbers | grep -v ACCEPT | head -30

# For AWS Security Groups — list rules for your web SG
aws ec2 describe-security-groups \
  --group-ids sg-xxxxxxxx \
  --query 'SecurityGroups[*].IpPermissions' \
  --output table

Add Cloudflare IP ranges to ufw (Ubuntu/Debian):

while IFS= read -r ip; do
  sudo ufw allow from "$ip" to any port 443
  sudo ufw allow from "$ip" to any port 80
done < /tmp/cf-ips-v4.txt

while IFS= read -r ip; do
  sudo ufw allow from "$ip" to any port 443
  sudo ufw allow from "$ip" to any port 80
done < /tmp/cf-ips-v6.txt

sudo ufw reload

Test TCP reachability from an external machine:

nc -zv YOUR_ORIGIN_IP 443
# Should print: Connection to YOUR_ORIGIN_IP 443 port [tcp/https] succeeded!

Step 4: Diagnose api.cloudflare.com Timeouts (Management API)

If your Terraform, CI/CD pipeline, or scripts are receiving timeouts when calling Cloudflare's management API:

Check Cloudflare API status:

curl -s https://www.cloudflarestatus.com/api/v2/status.json | \
  python3 -c "import sys,json; s=json.load(sys.stdin); print(s['status']['description'])"

Test API connectivity and latency:

curl -w "\nDNS: %{time_namelookup}s\nConnect: %{time_connect}s\nTTFB: %{time_starttransfer}s\nTotal: %{time_total}s\n" \
  -H "Authorization: Bearer $CF_API_TOKEN" \
  "https://api.cloudflare.com/client/v4/user/tokens/verify"

Check if you are hitting rate limits (Cloudflare API allows 1200 req/5min per token):

# Look for X-RateLimit-Remaining and X-RateLimit-Reset headers
curl -I -H "Authorization: Bearer $CF_API_TOKEN" \
  "https://api.cloudflare.com/client/v4/zones" 2>&1 | \
  grep -i 'ratelimit\|x-request-id\|cf-ray'

Step 5: Implement Async Pattern for Long-Running Endpoints

If your endpoint genuinely requires more than 100 seconds (report generation, bulk data export), the correct architecture is:

1. Client POSTs a job request → origin returns 202 Accepted with a job_id immediately
2. Origin processes in a background worker (Celery, Sidekiq, BullMQ)
3. Client polls GET /jobs/{job_id}/status (fast endpoint, always < 1s)
4. When status is complete, client fetches result from GET /jobs/{job_id}/result

This pattern eliminates all Cloudflare timeout concerns because no single HTTP request takes more than a second.