503 Unavailable error

[Richard]

We had 503 errors popping up randomly on some of our sites for a specific application. We upgraded to 4.0.10 and that seemed to stop the 503's from coming up when browsing the site, though when logging in it is triggering the 503 errors. The login page uses a redirect and is a POST request.

[mistwang]

Do you get 503 errors constantly?

[Richard]

For the most part when logging in, yes. Our server administrator and the software developers of the application both have said it seems to be a LiteSpeed problem.

[mistwang]

If the 503 error is not random, it maybe a problem with PHP build and PHP crashed. If switch back to Apache, you will get a blank page instead of 503 error page instead, that's all due to PHP crash. You can try different PHP version, turn off opcode cache, etc.