403 FORBIDDEN ERROR (jQuery)

Hello,
I can no longer insert an image (inside or outside the web server), when I using the console tool, I have it:
http://prntscr.com/n334ae (the red 4 means 4 errors after inserting 4 images)
The file corresponding to the error is the jQuery v1.12.4 file (line 4)

And I have a second problem, I think it’s linked but when a new member enters a team page they are automatically disconnected even if they reconnect, so they can’t join the teams.
Thanks for help.