Troubleshooting Guide

Common issues and their solutions when working with CronMonitor.

Monitor Shows "Down" But Job Is Running #

Symptoms #

• Your cron job executes successfully
• CronMonitor shows the monitor as "Down"
• No pings appear in the monitor history

Possible Causes & Solutions #

1. Wrong Ping URL #

Check:

# Log the ping URL your script is using
echo "Pinging: $PING_URL" >> /var/log/cronmonitor.log
curl -v "$PING_URL" 2>&1 | tee -a /var/log/cronmonitor.log

Solution:

• Copy the ping URL directly from the monitor details page
• Ensure no extra spaces or line breaks
• Use quotes around the URL in bash scripts

2. Network Connectivity Issues #

Test connectivity:

# Test if you can reach CronMonitor
curl -I https://cronmonitor.io
ping -c 4 cronmonitor.io

# Test with your actual ping URL
curl -v https://cronmonitor.io/ping/your-monitor-id

Common network issues:

• Firewall blocking outbound HTTPS
• DNS resolution problems
• Proxy configuration needed

Solution for proxy:

# Set proxy in curl
curl -x http://proxy.company.com:8080 https://cronmonitor.io/ping/abc123

# Set proxy in environment
export https_proxy=http://proxy.company.com:8080
curl https://cronmonitor.io/ping/abc123

3. Cron Job Failing Before Ping #

Problem:

# Job fails, ping never runs
0 2 * * * /path/to/backup.sh && curl https://cronmonitor.io/ping/abc123

Debug:

# Add logging to see what's happening
0 2 * * * /path/to/backup.sh 2>&1 | tee -a /var/log/backup.log && curl https://cronmonitor.io/ping/abc123

Solution: Check if your script is actually succeeding. Add error handling:

#!/bin/bash
set -e  # Exit on error

# Your backup logic
/usr/bin/mysqldump -u root database > backup.sql

# Only reached if above succeeds
curl https://cronmonitor.io/ping/abc123

4. SSL Certificate Issues #

Symptoms:

curl: (60) SSL certificate problem: unable to get local issuer certificate

Solution:

# Update CA certificates
sudo apt-get update
sudo apt-get install ca-certificates

# Or skip verification (not recommended for production)
curl -k https://cronmonitor.io/ping/abc123

5. Timeout Issues #

Symptoms: Long-running curl commands that timeout

Solution:

# Set reasonable timeout
curl -m 10 --retry 3 https://cronmonitor.io/ping/abc123

# Run in background
curl https://cronmonitor.io/ping/abc123 &

Wrong Schedule Detection #

Symptoms #

• Job runs successfully
• CronMonitor marks it as late or missed
• Times don't match expectations

Solutions #

Check Timezone Configuration #

Problem: Monitor timezone doesn't match your server

Verify server timezone:

date
timedatectl  # On systemd systems
cat /etc/timezone

Solution: Update monitor timezone in CronMonitor dashboard to match your server.

Verify Cron Expression #

Common mistakes:

# ❌ Wrong: This runs every minute, not daily at 2am
* 2 * * * /path/to/job.sh

# ✅ Correct: Runs daily at 2am
0 2 * * * /path/to/job.sh

Use crontab.guru to verify your expression.

DST (Daylight Saving Time) Issues #

During DST transitions, times can shift by an hour.

Solution:

• Use UTC timezone for monitors if possible
• Adjust grace period during DST transition weeks
• Consider using explicit times instead of cron expressions

Pings Received But Status Not Updating #

Possible Causes #

1. Using Wrong Monitor ID #

Check:

# Your ping URL should match the monitor
# Monitor ID: mon_abc123
# Ping URL: https://cronmonitor.io/ping/def456  ❌ Wrong!
# Ping URL: https://cronmonitor.io/ping/abc123  ✅ Correct

2. Monitor Is Paused #

Check: Monitor status in dashboard. If paused, it won't update.

Solution: Resume the monitor from the dashboard.

3. Browser Cache #

Solution:

• Hard refresh the page (Ctrl+F5 or Cmd+Shift+R)
• Clear browser cache
• Try incognito/private browsing mode

Grace Period Too Short #

Symptoms #

• Getting false alerts
• Job runs successfully but slightly late
• Alerts triggered during server load spikes

Solution #

Increase grace period to account for:

• Server load variations
• Network latency
• Job execution time variance

Example:

Job scheduled: 02:00:00
Job usually completes by: 02:00:30
Occasional delays up to: 02:02:00

Recommended grace period: 5-10 minutes

Learn more about grace periods →

Multiple Jobs Using Same Monitor #

Problem #

Multiple cron jobs pinging the same monitor causes confusion.

Bad:

0 2 * * * /backup-mysql.sh && curl https://cronmonitor.io/ping/abc123
0 3 * * * /backup-files.sh && curl https://cronmonitor.io/ping/abc123

Solution: Create separate monitors for each job:

0 2 * * * /backup-mysql.sh && curl https://cronmonitor.io/ping/mysql-backup-id
0 3 * * * /backup-files.sh && curl https://cronmonitor.io/ping/files-backup-id

Notifications Not Received #

Email Notifications #

1. Check Spam Folder #

CronMonitor emails might be filtered as spam.

Solution:

• Add [email protected] to your contacts
• Mark emails as "Not Spam"
• Add cronmonitor.io to your domain's SPF/DKIM whitelist

2. Verify Email Address #

Check your notification settings to ensure email is correct.

3. Email Service Issues #

Some corporate email servers have strict filtering.

Solution:

• Try a personal email address for testing
• Contact your IT department about whitelisting
• Use alternative notification channels (Slack, Webhook)

Slack Notifications #

1. Check Channel Permissions #

Ensure the CronMonitor app has permission to post in your channel.

2. Verify Integration #

• Go to Settings → Notifications → Slack
• Check if integration shows as "Connected"
• Try disconnecting and reconnecting

Webhook Notifications #

1. Endpoint Not Reachable #

Test your webhook:

curl -X POST \
  -H "Content-Type: application/json" \
  -d '{"test": true}' \
  https://your-webhook-endpoint.com/webhook

2. Verify Webhook Signature #

Make sure you're validating the signature correctly.

See webhook documentation →

API Issues #

401 Unauthorized #

Causes:

• Expired or invalid API token
• Token not included in request
• Token has wrong format

Solution:

# Check your request
curl -v \
  -H "Authorization: Bearer your-api-token" \
  https://cronmonitor.io/api/v1/monitors

# Generate new token if needed

429 Rate Limited #

Causes: Exceeded your plan's API rate limit.

Solution:

• Implement exponential backoff
• Cache API responses
• Upgrade to higher plan for more requests

Example backoff:

<?php
function apiRequest($url, $maxRetries = 3) {
    $attempt = 0;

    while ($attempt < $maxRetries) {
        $response = makeApiCall($url);

        if ($response->status !== 429) {
            return $response;
        }

        // Exponential backoff: 1s, 2s, 4s
        $delay = pow(2, $attempt);
        sleep($delay);

        $attempt++;
    }

    throw new Exception('Rate limited after retries');
}

PHP-Specific Issues #

file_get_contents() Fails #

Error:

Warning: file_get_contents(): SSL operation failed

Solution:

<?php
// Option 1: Use cURL instead
$ch = curl_init('https://cronmonitor.io/ping/abc123');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_exec($ch);
curl_close($ch);

// Option 2: Configure stream context
$context = stream_context_create([
    'ssl' => [
        'verify_peer' => true,
        'verify_peer_name' => true,
    ],
    'http' => [
        'timeout' => 10
    ]
]);

file_get_contents('https://cronmonitor.io/ping/abc123', false, $context);

allow_url_fopen Disabled #

Error:

Warning: file_get_contents(): https:// wrapper is disabled

Solution: Must use cURL:

<?php
$ch = curl_init('https://cronmonitor.io/ping/abc123');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_TIMEOUT, 10);
curl_exec($ch);
curl_close($ch);

Getting Help #

Before Contacting Support #

1. Check Monitor Status Page

   • Visit status.cronmonitor.io
   • Check for ongoing incidents

2. Review Recent Changes

   • Did you modify your cron schedule?
   • Did you update your server?
   • Did you change monitor configuration?

3. Collect Debug Information

   # Run this diagnostic script
   echo "=== CronMonitor Diagnostic ==="
   echo "Date: $(date)"
   echo "Timezone: $(cat /etc/timezone)"
   echo ""
   echo "=== DNS Resolution ==="
   nslookup cronmonitor.io
   echo ""
   echo "=== Connectivity Test ==="
   curl -I https://cronmonitor.io
   echo ""
   echo "=== Ping Test ==="
   curl -v https://cronmonitor.io/ping/your-monitor-id

Contact Support #

Include this information:

• Monitor ID
• Description of the issue
• Expected behavior vs actual behavior
• Recent changes to your setup
• Diagnostic output from above
• Relevant log entries

Email: [email protected] Chat: Available in dashboard

Community Help #

• GitHub Discussions: github.com/cronmonitor/community
• Stack Overflow: Tag with cronmonitor

Video Tutorial #

📺 Watch: "Troubleshooting Common Issues" (12 minutes)

Topics covered:

• Network connectivity issues (3:00)
• Schedule configuration (2:00)
• Notification problems (3:00)
• API troubleshooting (2:00)
• Getting help (2:00)

Quick Reference #

Debug Commands #

# Test ping manually
curl -v https://cronmonitor.io/ping/your-monitor-id

# Check cron logs
grep CRON /var/log/syslog

# View crontab
crontab -l

# Test cron expression
# Use: https://crontab.guru

# Check server time and timezone
date
timedatectl

Common Exit Codes #

Next Steps #

• Grace Period Best Practices →
• Critical Jobs Setup →
• Integration Examples →