The server cannot handle the request at present.
WHAT IT MEANS
Temporary unavailability. Different from a 500, which is a failure; this says try again.
COMMON CAUSES
The application is in maintenance mode Resource limits reached A service temporarily unavailable A plugin or security tool deliberately returning it
MAINTENANCE MODE
The most common cause on WordPress. A failed update leaves a .maintenance file in the site root.
Delete that file and the site returns immediately.
This happens when an update is interrupted.
RESOURCE LIMITS
Check cPanel > Resource Usage. If you hit entry processes or memory, requests are refused.
Enable caching, and check whether bot traffic is consuming capacity.
A PLUGIN RETURNING IT
Some security and maintenance plugins return 503 deliberately. Check whether one is configured to.
IF IT PERSISTS
Rename the plugins folder to disable everything and retest. That identifies whether the application is responsible.
WHAT TO SEND US
Whether a .maintenance file exists, and your resource usage for the period.
