Common Website, Errors 

Website errors can happen for many different reasons. A page may suddenly show 404 Page Not Found, a website may display 500 Internal Server Error, a domain may stop resolving because of a DNS problem, or WordPress may show a Critical Error.

Understanding the error code is the first step toward finding the correct solution. This guide explains the most common website, hosting, domain, DNS, SSL, server, PHP, database and WordPress errors, including what they mean, their common causes, and what you can check to troubleshoot them.

HTTP Website Errors

400 Bad Request

A 400 Bad Request error means the server cannot properly process the request sent by the browser or application.

Common causes

• Invalid URL or request parameters
• Corrupted browser cookies
• Invalid form submission
• Malformed HTTP request
• Application configuration problems
• Security or firewall rules blocking the request

How to fix it: Check the URL, refresh the page, clear browser cookies and cache, and review application or server logs if the problem continues.

401 Unauthorized

A 401 Unauthorized error usually means authentication is required before the requested resource can be accessed.

Common causes

• Incorrect username or password
• Expired login session
• Missing authentication credentials
• Incorrect API authentication
• Password-protected directories

Log in again and verify your credentials. For APIs, check authentication tokens and access credentials.

403 Forbidden

A 403 Forbidden error means the server understood the request but refuses to allow access to the requested resource.

Common causes

• Incorrect file or directory permissions
• Security plugin or firewall blocking access
• Blocked IP address
• ModSecurity rules
• Incorrect .htaccess configuration
• Directory access restrictions

Check file permissions, directory permissions, .htaccess, security rules, ModSecurity and server logs.

404 Page Not Found

404 Not Found is one of the most common website errors. It means the server cannot find the requested page, file or resource.

Common causes

• Incorrect URL
• Deleted page or file
• Renamed page
• Broken internal link
• Incorrect WordPress permalink
• Missing file
• Incorrect rewrite rules
• Incorrect .htaccess configuration

WordPress 404 error

If your WordPress homepage works but individual pages or posts return 404, go to WordPress Dashboard → Settings → Permalinks and click Save Changes. This can regenerate the WordPress rewrite rules.

If the problem continues, check the .htaccess file and web server rewrite configuration.

405 Method Not Allowed

A 405 Method Not Allowed error occurs when the server understands the HTTP request method but does not allow that method for the requested resource.

This is more common with APIs and web applications. Check the application routing configuration, server configuration and HTTP method being used.

408 Request Timeout

A 408 Request Timeout occurs when the server does not receive a complete request within the expected time.

Possible causes include slow network connections, overloaded servers, proxy timeouts and slow applications.

409 Conflict

A 409 Conflict indicates that the request conflicts with the current state of a resource. It is commonly encountered with APIs and web applications.

410 Gone

A 410 Gone response indicates that a resource has been intentionally removed and is no longer available.

If a page has moved to a replacement URL, a 301 redirect may be more appropriate.

429 Too Many Requests

A 429 Too Many Requests error means that too many requests have been received within a specific period.

Common causes

• API rate limits
• Excessive requests
• Bot traffic
• Brute-force login attempts
• Aggressive scripts
• Security or firewall rules

If you manage the website, check access logs, rate limits, firewall rules and bot traffic.

Server Errors

500 Internal Server Error

A 500 Internal Server Error is a generic server-side error indicating that something unexpected prevented the server from completing the request.

Common causes

• PHP fatal error
• Broken .htaccess
• PHP version incompatibility
• WordPress plugin conflict
• WordPress theme problem
• Incorrect server configuration
• File permission problems
• Memory or resource limitations

Check the website's PHP error logs and server error logs to identify the actual cause instead of making multiple configuration changes at once.

502 Bad Gateway

A 502 Bad Gateway error usually occurs when a proxy, gateway or web server receives an invalid response from an upstream server.

Common causes

• PHP-FPM failure
• Backend server unavailable
• Reverse proxy problems
• Application crash
• Server overload
• Network problems

Check the origin server, PHP-FPM, web server logs, server resources and firewall configuration.

503 Service Unavailable

A 503 Service Unavailable error generally means that the server is temporarily unable to handle the request.

Common causes

• Server maintenance
• High CPU usage
• High RAM usage
• Hosting resource limits
• PHP-FPM process limits
• Application overload

Check server resources and service status. If you are using shared hosting, contact your hosting provider if the problem continues.

504 Gateway Timeout

A 504 Gateway Timeout occurs when a gateway or proxy does not receive a response from the upstream server within the expected time.

Common causes

• Slow PHP scripts
• Slow database queries
• Server overload
• Long-running API requests
• CDN or reverse proxy timeout

Check PHP execution time, database queries, server resources and application performance.

DNS and Domain Errors

DNS_PROBE_FINISHED_NXDOMAIN

DNS_PROBE_FINISHED_NXDOMAIN generally means that DNS could not find the requested domain name.

Common causes

• Domain does not exist
• Domain has expired
• Incorrect nameservers
• Missing DNS zone
• Incorrect DNS records
• Domain registration problem

Check the domain registration status, nameservers, DNS zone and DNS records.

ERR_NAME_NOT_RESOLVED

ERR_NAME_NOT_RESOLVED generally means that the domain name could not be resolved to an IP address.

Check the domain's nameservers, A record, CNAME record, domain status and DNS configuration.

DNS_PROBE_FINISHED_BAD_CONFIG

This browser error can indicate a DNS configuration or DNS resolution problem.

Check your domain's DNS records, nameservers and local DNS cache. Testing the website from another network can also help determine whether the issue is local or global.

Domain Points to the Wrong Website

If your domain opens another website or the wrong hosting account, check the A record, nameservers, hosting IP address and virtual host configuration.

Old DNS records or cached DNS information can also cause temporary confusion after a DNS change.

SSL and HTTPS Errors

NET::ERR_CERT_DATE_INVALID

This error usually means the SSL certificate is expired, not yet valid, or the device/server date and time are incorrect.

Check the SSL certificate's validity period and make sure the correct certificate is installed for the domain.

NET::ERR_CERT_COMMON_NAME_INVALID

This error occurs when the SSL certificate does not properly match the hostname being accessed.

Common causes

• Incorrect SSL certificate
• Missing www hostname
• Incorrect virtual host
• Incorrect CDN SSL configuration

ERR_SSL_PROTOCOL_ERROR

This error means the browser could not establish a valid SSL/TLS connection with the server.

Check SSL certificates, TLS settings, CDN configuration, proxy settings and web server HTTPS configuration.

Mixed Content Warning

Mixed content occurs when an HTTPS page loads resources such as images, JavaScript or CSS files over HTTP.

For example, an HTTPS website may contain an image URL beginning with http://.

Update insecure resource URLs to HTTPS and make sure all required resources are available securely.

WordPress Errors

WordPress Critical Error

The WordPress message "There has been a critical error on this website" generally indicates a serious PHP or application error.

Common causes

• Plugin conflict
• Theme conflict
• PHP fatal error
• PHP version incompatibility
• Memory limitation
• Corrupted WordPress files
• Custom PHP code error

Check the WordPress debug log and PHP error logs. If the problem started immediately after a plugin or theme update, investigate that change first.

Error Establishing a Database Connection

This error means WordPress cannot connect to its MySQL or MariaDB database.

Common causes

• Incorrect database credentials
• Incorrect database hostname
• Database server unavailable
• Database corruption
• Too many database connections
• Database user permission problems
• Server resource exhaustion

Check the WordPress database configuration and database server status. Database and server logs can provide additional information.

WordPress White Screen

A completely blank WordPress page can be caused by a PHP fatal error, plugin conflict, theme problem, memory exhaustion or PHP compatibility issue.

Enable appropriate debugging/logging and inspect PHP error logs to identify the underlying problem.

WordPress Too Many Redirects

A redirect loop occurs when the browser is repeatedly redirected between URLs and eventually stops.

Common causes

• HTTP/HTTPS mismatch
• Incorrect WordPress URL
• Incorrect Site URL
• Conflicting redirect rules
• CDN SSL configuration
• Security or redirect plugins
• Incorrect .htaccess

Check the WordPress URL settings, HTTPS configuration, CDN settings and redirect rules.

WordPress 404 on Posts and Pages

If the WordPress homepage works but posts or pages return 404 errors, the problem may be related to WordPress permalink or rewrite configuration.

Go to WordPress Dashboard → Settings → Permalinks and click Save Changes. If the problem continues, check the .htaccess file and server rewrite configuration.

WordPress Login Problems

WordPress login problems can be caused by incorrect URLs, cookies, security plugins, SSL configuration, redirect rules, .htaccess or plugin conflicts.

Test the login page in a private/incognito browser window and check WordPress, PHP and server logs if the problem continues.

PHP Errors

PHP Fatal Error

A PHP fatal error prevents the PHP application from continuing execution and can result in a 500 error or WordPress critical error.

Check the PHP error log for the exact file, line number and error message.

PHP Memory Limit Exhausted

An error such as "Allowed memory size exhausted" means a PHP process reached its configured memory limit.

Common causes

• Heavy WordPress plugins
• Large imports
• Image processing
• Complex database operations
• Inefficient application code

Investigate the application or plugin consuming excessive memory before simply increasing the memory limit.

Maximum Execution Time Exceeded

This occurs when a PHP script takes longer than the configured maximum execution time.

Large imports, backups, slow APIs, heavy plugins and slow database operations are common causes.

Hosting and Server Resource Errors

Website Loading Slowly

A slow website does not always mean the hosting server is down.

Possible causes

• Large images
• Unoptimized JavaScript
• Too many plugins
• Slow database queries
• High server load
• Poor caching
• External API delays
• Insufficient hosting resources

Check website performance, server resource usage, database queries, caching and image optimization.

CPU Usage Limit Reached

High CPU usage can be caused by heavy traffic, bots, WordPress plugins, cron jobs, malware, inefficient scripts or database queries.

Review your hosting resource usage and identify which process or website is consuming CPU resources.

Memory Usage Limit Reached

High memory usage can cause PHP failures, slow websites, database problems and service interruptions.

Check running processes, PHP workers, database usage and application requirements.

MySQL Too Many Connections

This error means the database server has reached its configured connection limit.

Common causes

• High traffic
• Long-running database queries
• Poor application connection handling
• Insufficient database configuration
• Server resource limitations

Check active connections, slow queries, database configuration and server resource usage.

File and Permission Errors

Permission Denied

A permission error occurs when the operating system or web server does not have the required permission to access a file or directory.

Check file ownership, directory ownership and permissions. Avoid applying unnecessarily broad permissions because they can create security risks.

.htaccess Errors

A broken .htaccess file can cause 500 errors, redirect loops, 403 errors, 404 errors and broken WordPress permalinks.

If the error started after an .htaccess change, review the latest configuration and restore a known-good configuration if necessary.

How to Troubleshoot Any Website Error

1. Record the exact error

Write down the exact error message and status code, such as 404, 403, 500, 502, 503, 504 or a DNS/SSL browser error.

2. Determine what is affected

Check whether the problem affects one page, the entire website, WordPress admin, one device, one network or all visitors.

3. Check recent changes

Think about what changed immediately before the problem appeared. This could be a plugin update, theme update, PHP version change, DNS change, SSL change, server migration or configuration change.

4. Check DNS

Verify the domain's A record, AAAA record, CNAME, nameservers and DNS configuration.

5. Check SSL

Verify the SSL certificate, hostname coverage, HTTPS configuration and redirects.

6. Check hosting resources

Review CPU, RAM, disk space, PHP processes, database connections and server load.

7. Check logs

Logs are often the most useful source of information when troubleshooting a technical problem.

• Web server error logs
• PHP error logs
• WordPress debug logs
• Database logs
• Firewall/security logs
• Application logs

8. Avoid changing multiple settings at once

Make one change at a time and test the website after each change. This makes it much easier to identify the actual cause of the problem.

When Should You Contact Your Hosting Provider?

Contact your hosting provider when the problem appears to be related to the hosting server or infrastructure.

Examples include:

• Server is unreachable
• Persistent 500, 502, 503 or 504 errors
• PHP-FPM problems
• Database service problems
• Hosting resource limits
• Disk space problems
• Firewall or network problems
• DNS configuration problems
• SSL installation problems
• Server configuration problems

Information to provide in a support ticket

• Domain: Your domain name
• Error: Exact error message or code
• Affected URL: The URL where the problem occurs
• Time: When the problem started
• Recent changes: Any recent website or server changes
• Screenshot: Screenshot of the error if available

Providing these details can help your hosting support team investigate the problem more efficiently.

Final Thoughts

Website errors are not random messages. Each error provides a clue about where a problem may exist between the visitor, domain, DNS, network, web server, PHP application and database.

A 404 usually indicates that a requested resource cannot be found. A 403 indicates that access is being refused. A 500 indicates an unexpected server or application error, while 502, 503 and 504 can indicate backend, availability or timeout problems.

For WordPress websites, plugins, themes, PHP, databases, permalinks, .htaccess and hosting resources can all contribute to an error.

The best approach is to identify the exact error, determine which layer is affected, check recent changes and review the relevant logs before making configuration changes.

Need help with your website or hosting account?

If you are an Unlimited.pk customer and cannot resolve a website, hosting, domain, DNS, SSL or server problem, please contact our support team through your client area and provide the exact error message, affected domain and any relevant screenshot.

We are here to help you keep your website online and running reliably.