Are you now missing the reading pane perhaps? (F8)

Hello Matt. F8 OK, but nothing in this reading pane (but before the last version it was good). Damned ! Richard

If the Message Pane is blank, open Preferences/General and look at hardware acceleration (at the bottom). If it's enabled, uncheck the box, restart TB, and see if there's any difference.

Hello. I try it, but allways nothing ! Can I uninstall TB and then re-install TB ? Thank's Richard

Do you have same issue if you restart Thunderbird in SAfe Mode?

It is possible something maybe wrong as this was a new install. There is no harm in uninstalling the program and then getting a fresh download and reinstalling. https://www.thunderbird.net/en-US/thunderbird/all/

If it looks correct in safe (troubleshoot) mode, (hold Shift when launching TB), then the other possibility is a broken layout. Start again in safe mode, 'Reset toolbars & controls', 'Make changes & restart'.

Hello. Yes, it is correct in the safe mode, BUT only if I open TB in this mode ! No good for next opening TB. Thank's Richard

Hello. Yes, it is correct in the safe mode, BUT only if I open TB in this mode ! No good for next opening TB. Thank's Richard

Did you then try: Start again in safe mode, at prompt select checkboxes 'Reset toolbars & controls' and then click on 'Make changes & restart'.

If you tried that as well and still not working in normal mode........ What addon extensions are you using ? Menu app icon > Addons > Extensions Disable the first addon extension and restart Test message appears in Message Pane. If this works then the addon is causing the problem. You may need to repeat disabling an addon and restarting to locate which addon is the problem.