Unknown CORS header ‘Access-Control-Allow-Origin’ missing error

Problem Description:

There are many reasons for getting a CORS error.  For example,  you may be getting the error:

CORS header ‘Access-Control-Allow-Origin’ missing

If you have tried all known configurations and it is still not working, the cause may be a bug in Apache httpd.

Workaround:

a) Check and see if you are using Apache httpd.

b) Check this link for details on this bug,

https://bz.apache.org/bugzilla/show_bug.cgi?id=61820https://bz.apache.org/bugzilla/show_bug.cgi?id=61820

c) Try nginx if possible, to see if it works better.