Error pages and blank screens
Blank white page
Usually: PHP fatal error with display of errors turned off. Often a plugin or theme conflict, an incompatible PHP version, or a memory limit.
- Look in the error log for the file and line.
- Rename the plugins folder via SFTP to disable all plugins at once; if the site returns, re-enable them one by one.
- Check whether PHP was recently upgraded.
- Raise the memory limit and see if the error changes.
500 Internal Server Error
Usually: A generic failure. The usual sources are a syntax error in .htaccess, wrong file permissions, or a PHP crash.
- Read the error log, which will usually name the cause.
- Rename .htaccess and reload. If it works, rebuild the file.
- As a typical baseline, folders are 755 and files 644.
- Check whether you hit a resource limit.
Error establishing a database connection
Usually: Wrong credentials, database server stopped, or the account hit a connection limit.
- Check credentials in the config file.
- Try connecting with the command line client.
- Ask the host whether the database service is healthy.
- Look for a traffic spike or bot attack.
Too many redirects
Usually: Conflicting HTTP and HTTPS rules, or the CDN and the server each trying to enforce their own.
- Follow the chain with curl -IL.
- Keep redirect rules in one place.
- Check the CDN encryption mode.
Cannot upload large files
Usually: PHP and web server limits for upload size and execution time.
- Raise upload_max_filesize and post_max_size.
- Check web server body size limits.
- Use SFTP for very large files.
403 Forbidden on a page that used to work
Usually: File permissions changed, an .htaccess rule or security plugin blocking the request, or a firewall rule.
- Check the error log for the rule that fired.
- Compare file and folder permissions with a working page.
- Temporarily rename .htaccess to see if it is the cause.
- Look at the firewall or WAF log for the blocked request.
404 on every page except the homepage
Usually: Permalink rewrite rules missing or the server not reading .htaccess.
- In WordPress, re-save the permalink settings to regenerate rules.
- Check that .htaccess exists and is readable.
- Confirm the web server allows overrides for the site's folder.
- On Nginx, check the try_files rule.
502 Bad Gateway
Usually: The proxy could not get a valid reply from PHP-FPM or the application server.
- Check whether the PHP service is running.
- Read the PHP-FPM and web server error logs.
- Look for a worker limit or a crashed process after a long script.
- Ask the host whether the server was restarted.
503 Service Unavailable
Usually: Resource limits reached, a maintenance flag left behind, or the application is overloaded.
- Look for a .maintenance file in the WordPress root and delete it if an update was interrupted.
- Check usage graphs for CPU, memory and entry processes.
- Look for bot traffic in the access log.
Site stuck in maintenance mode after an update
Usually: An update was interrupted and left the maintenance marker behind.
- Delete the .maintenance file from the site root.
- Re-run the update after checking free disk space.
- Clear caches.
Uploads fail with a generic error
Usually: Disk quota full, wrong folder permissions or size limits.
- Check free disk space and inode count.
- Confirm the uploads folder is writable.
- Review upload_max_filesize, post_max_size and web server body limits.
The site shows a different site's content
Usually: A DNS record points at the wrong server or the server's virtual host is not configured for your domain.
- Compare the IP in DNS with the one your host gave you.
- Make sure the domain is added to the hosting account.
- Check for a default site catching unknown hostnames.