there is a patch available for this that needs to be applied to irssi for focal
from GitHub issue:
"A change in GLib 2.63 broke some assumptions in Irssi that the null-byte NUL / U+0000 is a valid Unicode character. This would occur when the user types Ctrl+Space. As a result, the input loop never manages to process the NUL-byte (and any other user input that follows, ever).
This affects all versions of Irssi as soon as your system is updated to this GLib version."
see https:/ /github. com/irssi/ irssi/issues/ 1180
there is a patch available for this that needs to be applied to irssi for focal
from GitHub issue:
"A change in GLib 2.63 broke some assumptions in Irssi that the null-byte NUL / U+0000 is a valid Unicode character. This would occur when the user types Ctrl+Space. As a result, the input loop never manages to process the NUL-byte (and any other user input that follows, ever).
This affects all versions of Irssi as soon as your system is updated to this GLib version."