Sometimes we upload the whole PHP web application folder onto the share hosting environment, e.g. /xxx/public_html/phpapp.
However, when we access http://www.xxx.com/phpapp, there is 402 or 500 Internal Error.
Checking the backend log, the error message is:
"Premature end of script headers"
Solution: we need to chmod the whole phpapp directory recursively to the following read write access.
Command Line: chmod 745 -R /xxx/public_html/phpapp