Knowledgebase

503 & 508 Errors (Resource Limits) – Firstserv Guide

If you encounter a 503 (Service Unavailable) or 508 (Loop Detected) error, it usually means your hosting account temporarily cannot handle the request.

What Causes These Errors?

In most cases, these errors occur because your account has reached one or more resource limits, such as:

• CPU usage
• Memory (RAM)
• Disk I/O
• Entry processes (simultaneous connections)

⚠️ In rare cases, the issue may be related to temporary server maintenance or downtime—but this is uncommon.

Common WordPress Cause

A frequent issue with WordPress sites is the built-in WP-Cron system, which can trigger excessive background processes.

👉 We recommend:

• Disabling the default WordPress cron
• Replacing it with a cPanel cron job

This can significantly reduce resource usage and prevent errors.

How to Check Resource Usage in cPanel

Step 1: Open Resource Usage

1. Log in to cPanel
2. Go to Metrics → Resource Usage

Step 2: Check the Status

You may see one of the following messages:

• ✅ “Your account has not been limited”
  → No issues detected

• ⚠️ “Your account has been limited”
  → Your site has exceeded one or more limits

• ⚠️ “Your site may hit resource limits soon”
  → Usage has exceeded 90% of available resources

Viewing Detailed Usage

Click Details to see:

• Which resources were limited
• When the limits were reached
• Historical usage (default: last 24 hours)

Understanding Resource Metrics

CPU Usage

• Maximum allowed: 100% (1 core)
• High average usage = potential issue
• Short spikes are normal

Memory (RAM)

• Shows how much memory your processes use
• High usage isn’t always a problem (Linux uses caching efficiently)

Input/Output (I/O)

• Measures read/write activity on disk
• High usage may indicate heavy file/database activity

IO Operations

• Number of file or network operations
• Includes opening files or making external connections

Entry Processes

• Number of concurrent requests
• Example: visitors accessing your site simultaneously
• Too many slow processes can exhaust this limit

Total Processes

• Total processes running under your account
• Includes entry processes

Faults

Tracks when limits are exceeded, including:

• CPU faults
• Memory faults
• Entry process limits
• I/O limits

✅ Helps identify what triggered the issue.

Advanced Troubleshooting

Use the Snapshots tab to:

• View specific points in time
• See which processes were running
• Identify scripts or requests causing high usage

How to Resolve Resource Issues

Common Fixes

• ✅ Optimise your website (plugins, themes, code)
• ✅ Reduce or replace heavy plugins
• ✅ Enable proper caching (e.g. LiteSpeed Cache)
• ✅ Optimise database queries
• ✅ Disable inefficient background tasks (e.g. WP-Cron)

Traffic & Growth

If your site is growing or receiving more traffic:

• Consider upgrading your hosting plan for more resources

Summary

A 503 or 508 error is usually caused by hitting resource limits on your hosting account.

To resolve:

1. Check usage in cPanel → Resource Usage
2. Identify which resource is being limited
3. Optimise your website or processes
4. Upgrade your plan if required

If you need help analysing your resource usage or identifying the root cause, the Firstserv support team is always available to assist.