Clone tool taking too long and most of the time it give 502 error


I am using your clone tool and its taking too long to start cloning process and most of the time it gives 502. When I say too long its does not mean cloning time. When we filling out all information and press start, then it take ages to go to cloning page and most of the time it throws 502 error. I have my site hosted on WPEngine . I have also attached error log file, please check and kindly fix this issue ASAP. Thanks