I have a script that I run that often results in 504 Gateway Timeout Errors, and thus the virtual user fails; however, even when I get this error I might end up with 2 passed and 3 failed virtual users, but still all the functions all 5 users are performing were successful including e-mails that get produced.
I have timeout settings in the controller off, and I also have the timeouts in run time settings set to 600 seconds so that if there is a very slow response time or timeout it is not because of loadrunner, but because of the application.
From talking with the application team developer lead there is a 500ms delay after the function where the error occurs, although, as I have said all the virtual users complete this function and everything that is expected is fine.
Could a 500ms delay after that function be enough to trigger this 504 Gateway Timeout Error?
504 Gateway Timeout error indicates that one of your chain servers is not responding to the other server in your chain request in the time alloted (say 120 seconds or as per the configuration file). This is more of a network issue rather than your script or performance center issue.
Passed transactions you are observing are because of the delayed responses received during which otherwise timeouts occured at 'PC' level.
I would suggest you to put think time of more than 800sec after the designated function which requests for the email to verify the network delays.