I was able to recreate this on a 20.04 daily iso dated 20200330 by clicking quit after selecting a language. This happens both when choosing "Install Ubuntu" or launching "Install Ubuntu" from the desktop.
** Tags added: focal -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1755452 Title: ubiquity crashed with ValueError in command(): I/O operation on closed file. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1755452/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs