HTTP error codes provide clues as to why a website or service is not accessible. The following errors occur particularly frequently in web hosting.
Meaning
Access to the requested resource is not allowed.
Common causes
Incorrect file or folder permissions (e.g. 777 or 000)
Missing start file (index.php, index.html)
Access blocked by security rules (firewall / ModSecurity)
Access restrictions in the .htaccess
What you can do
Check the file permissions:
Folders: 755
Files: 644
Make sure a start file is present
Temporarily disable security plugins or protection mechanisms for testing
Check existing .htaccess rules
Meaning
The request was rejected by the server due to security or content rules.
Common causes
ModSecurity blocks certain parameters or forms
Suspicious characters in URLs or form fields
Misconfigured plugins or themes
What you can do
Remove special characters from URLs or forms
Temporarily disable plugins or web application firewalls for testing
Test the site without individual .htaccess rules
Contact support with the affected URL
Meaning
Too many requests have been sent to the server in a short time.
Common causes
Bots or crawlers access the website too frequently
Misconfigured plugins (e.g. cron jobs or API queries)
External services or scripts with high request frequency
What you can do
Check and limit cron jobs or API accesses
Enable caching (e.g. browser or server cache)
Block suspicious IP addresses
Reduce automatic background queries
Meaning
The server cannot correctly execute or interpret the application.
The exact cause is initially unknown.
Common causes
PHP errors or incompatible PHP version
Broken or faulty plugins/themes
Too low PHP memory limit
What you can do
First check the php_error.log
(in the home directory under /log)
Temporarily set the PHP version to an older/stable version
Temporarily rename the .htaccess
Disable plugins step by step
Meaning
The web server receives an invalid response from a connected service
(e.g. PHP-FPM).
Common causes
PHP process crashed or overloaded
Too long script runtimes
Misconfiguration between web server and PHP
What you can do
Reload the page (often a temporary problem)
Reduce the complexity of plugins or scripts
If necessary, increase PHP limits (memory / execution time)
Check recently changed PHP settings
Meaning
The server is currently unavailable.
Common causes
Server overload
Maintenance work
Too many concurrent processes
Service restarts
What you can do
Wait a few minutes and reload the page
Check whether updates or maintenance are running
Reduce concurrent accesses (e.g. through caching)
Contact support if the error persists
Meaning
A connected service took too long to respond.
Common causes
Very slow database queries
Unreachable external APIs
Long script runtimes or large data processing
What you can do
Optimize plugins and database queries
Temporarily disable external services for testing
Reduce import or export processes
Many of these errors are configuration- or load-related and often occur after the following changes:
Updates
Plugin installations
PHP version changes
Traffic peaks
If an error is reproducible or persists for a longer time, support will be happy to assist.
Please provide as much as possible:
the affected URL
the time of the error
a brief description of recent changes