Background CSS images won't be changed after reuploading & Cache flushing If I Download a css background image of my site, changing it with GIMP (or MS paint for that matter) and re upload it, nothing will happen. Moreover, even after I delete the file from the server, the image stays online... clicking "Flush all caches" nothing happens... I also note that the image basically stays the same --- Same filename and file extension, so it's extremely wired. What would you suggest of checking?

What I already tried and didn't help:


Turning off server external caching tool (for both static and dynamic cache).
Turning off AdvAgg from config/development/performance/advagg (Unchecked "Enable...")
Turning off Drupal's internal cache system.


Update: Working answer found... See below for the answer with green checkmark.
Since all caching aren't able to fix, let's try narrowing down the issue.

First, try to delete the image from your theme. Flush all caches and see if the background image is still there. If it is, open your browser development tool and check the background image URL and try opening it in a new tab, check the URL of the image and follow it in your server's directory if it really still exists.

Second, try restarting the server or any related running services you have in your server.

Hope this can at least give an idea on where to find what's causing the issue.