A workaround is to disable pdfjs in the config editor. Credit to scottishjon55 on reddit
See https://www.reddit.com/r/Thunderbird/comments/qrpmnb/cant_open_attachments_while_composing/ -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1981163 Title: [upstream] In Compose window, if a PDf is joined and clicked to open, Thunderbird launches Firefox instead of Evince To manage notifications about this bug go to: https://bugs.launchpad.net/thunderbird/+bug/1981163/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
