It's working here on 115.2.2. Does it work in safe/troubleshoot mode? Hold Shift when launching TB.

It works when activated from the main menu bar. When you have a message open and you go to the menu bar of the message window it it grayed out.

The vast majority of time that I turn on/off view headers is when I am interested in the headers of a particular message that I am reading. If it is not going to be alliable from the message window, It should not even show up in the menu for a message.

In TB 102, the headers option is accessible in a message window, but its absence in 115 is either a bug or a design change. You could submit a report to Bugzilla. In the meantime, headers can be seen in the message source (Ctrl+U).

I have no option to switch from normal headers to full headers in this Thunderbird version ? I always used to use 'full view' if forwarding hoax emails I haven't got ANY Headers options on the toolbar

I have no option to switch from normal headers to full headers in this Thunderbird version ? I always used to use 'full view' if forwarding hoax emails I haven't got ANY Headers options on the toolbar

Headers is under View on the Menu Bar. Press Alt if the Menu Bar is hidden.