Unable to save user data in version 8.2.3

Hi
I'm unable to save any change to an existing user on version 8.2.3. I'm logged as Administrator.
The animated loader displays for a moment, then disappera without any message explaining the reason of the failure.
If I explore in Chrome I can see there is a failure as exposed in the attached picture.


May you kindly put me in the right direction to get rid of this?
Many thanks in advance.

Hi Babynus.
Many thanks for your suggestions.
I investigated my Apache 2.4 configuration and found nothing related to a possible 403 error.

So, I read the XMLHttpRequest response with more attention,and found this entry:
statusText: "Blocked by Bitdefender"
which is the antivirus I installed on the machine where Apache runs.

This probably explains most part of problems I'm facing ...
Many thanks again to put me in the right direction.

Regards