Between 2017 and 2020 there was an ultimately unsuccessful attempt to breathe
new life into the KornShell by extensively refactoring the last unstable AST
beta version (93v-). While that ksh2020 effort is now abandoned and still has
many critical bugs, it also had a lot of bugs fixed. More importantly, the AST
issue tracker now contains a lot of documentation on how to fix those bugs,
which made it possible to backport many of them to the last stable release
instead. This ksh 93u+m reboot now incorporates many of these bugfixes, plus
patches from OpenSUSE, Red Hat, and Solaris, as well as many new fixes from the
community (1, 2). Though there are many bugs left to fix, we are confident at
this point that 93u+m is already the least buggy version of ksh93 ever
released. As of late 2021, distributions such as Debian and Slackware have
begun to package it as their default version of ksh93.