Error image in Extension list

Clicking an extension in the extension list (menu Applicatoons - Extensions) results in this “Error” image. What is the meaning of it? It does not show any adddional information.
I hope someone can help me.

Does this happen right after you have logged in? I’ve seen this message usually I just need to refresh the page and login again.

Hi!

Try to clear your browser cache…

If this doesn’t fix it I would suggest to check if someone has reported the same problem on https://issues.freepbx.org and if not open a ticket…

Good luck and have a nice day!

Nick

It does not only happen right after login but also later.
Refreshing the page and login does not help.
The strange thing is that I see so other functional problem (except that my YeaLink W52 IP DECT phone loses its registration every time, but I don’t know if that problem is related to this error)
I’m just suspicious about the reason of the error.
The red box with “Error” seems to be a hyperlink (moving the mouse cursor on it changes it to a hand) but clicking the box has no effect.

Unfortunately clearing the browser cache does not help