Hi All,
Here is final solution for API issue, when your API is not working or showing HTTP 404 error you means your .htaccess is not working just go to apache config file check AllowOverride option and change the AllowOverride None to AllowOverride All.
Now try again API url you should receive the internal server error means the our .htaccess is working but we did not enabled the apache mod_rewrite. use below command to enable mod_rewrite a2enmod rewrite then restart the server.
Note: If you install the separate apache server then and then only you will get this issue but you taken apache2 from OpenEMR site it will not going issue you because they already made that changes into the apache2 server.
Thanks,
Nilesh