A fix has been merged upstream two months ago, see https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4184 and https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2027
The fix was released with version 40.6, but Debian and Ubuntu haven't updated the upstream package in their repository, yet. ** Bug watch added: gitlab.gnome.org/GNOME/gnome-shell/-/issues #4184 https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/4184 -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/1933996 Title: Alt-tab stops switching windows [JS ERROR: TypeError: window is null _createWindowClone@resource:///org/gnome/shell/ui/altTab.js:29:27] Status in GNOME Shell: Unknown Status in mutter package in Ubuntu: Fix Committed Bug description: When a new Wayland session is created from a login, Alt-tab works as expected to change windows. After sometime Alt-tab fails to do anything (super-tab still works to change applications) and the following error is created in syslog: gnome-shell[777718]: JS ERROR: TypeError: window is null#012_createWindowClone@resource:///org/gnome/shell/ui/altTab.js:29:27#012_init@resource:///org/gnome/shell/ui/altTab.js:1004:34#012_init@resource:///org/gnome/shell/ui/altTab.js:1045:24#012_init@resource:///org/gnome/shell/ui/altTab.js:568:30#012_startSwitcher@resource:///org/gnome/shell/ui/windowManager.js:2069:24 The only workaround I have found is to logout and log back in, however after some time the error repeats itself. Ubuntu 21.04 gnome-shell: Installed: 3.38.4-1ubuntu3~21.04.1 ProblemType: Bug DistroRelease: Ubuntu 21.04 Package: gnome-shell 3.38.4-1ubuntu3~21.04.1 ProcVersionSignature: Ubuntu 5.11.0-22.23-generic 5.11.21 Uname: Linux 5.11.0-22-generic x86_64 ApportVersion: 2.20.11-0ubuntu65.1 Architecture: amd64 CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Tue Jun 29 10:53:32 2021 DisplayManager: gdm3 InstallationDate: Installed on 2020-11-11 (230 days ago) InstallationMedia: Ubuntu 20.10 "Groovy Gorilla" - Release amd64 (20201022) RelatedPackageVersions: mutter-common 3.38.4-1ubuntu2 SourcePackage: gnome-shell UpgradeStatus: Upgraded to hirsute on 2021-04-27 (62 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/gnome-shell/+bug/1933996/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp