Intermittent PHP include failures on Microsoft IIS

This is an answer to my own StackOverflow question that I can not answer over there because of lacking enough reputation.

This issue was due to a missing permission. What I eventually found out is that PHP (or one of its modules like php_wincache.dll) wants Execute/Traverse permissions in the website’s root directory.

With the help of SysInternals Process Monitor I noticed that the following CreateFile call was failing with Access Denied. Note in the desired access field is asking for Execute/Traverse

After that, PHP tries to load the include file from the wrong location.

Solution: granting Execute/Traverse in the website’s root directory to the identity under which the PHP process is running solve the intermittent ‘No such file or directory’ include issue.