Since upgrading to version 128.3.3esr (Build 20241023091249) on Arch Linux sending messages does not work any more. After clicking the '''Send''' button, choosing '''Send''' in the toolbar menu, or using '''<Ctrl>+<Enter>''', all buttons and the toolbar menu becomes inactive (greyed out), but the message is not send. The behavior occurs on different mail accounts. When starting Thunderbird from the terminal the following error occurs: ''JavaScript error: moz-extension://cd757c35-cc8e-45ec-b1a7-c66dfbe94276/background.js, line 3070: TypeError: action is undefined'' Restarting Thunderbird in safe-mode resolves this issue and there is no error message in the terminal. Deactivating add-ons one by one, as mentioned in [[https://support.mozilla.org/en-US/questions/1120568|question 1120568]], reveals that [https://addons.thunderbird.net/de/thunderbird/addon/cardbook/ CardBook] seems to be causing this issue. For this reason, I sent a copy of this question to the add-on support contact.