Getting X-Frame-Options issues, but with an AJAX file

Hi all,

Full disclosure: I an new to Drupal and am really struggling to get my head around it, so please keep that in mind if answering.

I’m setting up a site on my local dev box. I have to set up a module here, which I have mostly done, but I am getting an error when I trigger the module’s AJAX functions:

[Report Only] Refused to display ‘‘ in a frame because an ancestor violates the following Content Security Policy directive: “frame-ancestors ‘none'”.

Looking this up on Google, I see that this is mostly an iframe related error, with the remote server not allowing its content to be embedded.

However, this is neither an iframe, nor from a remote site.

I found this documentation about setting X-Frame-Options:

and so tried adding

$conf['x_frame_options'] = 'SAMEORIGIN';

to my global settings.php file, but this made no difference.

Would anyone know what I could try to get this working?

Drupal version: