I recently had a similar issue with MacOS with Apache as my web server. Working with WRC, we found that Apache was running as a user (_www) that did not have access to the InterSystems IRIS files. In my case, the solution was to go into the httpd.conf file and edit the user that Apache runs as such that it does have access (in my case, we just used irisusr for simplicity as I'm not using the web server for anything else). Hope this helps anyone running into similar issues!