I have the same problem after updating to 20.04.1. An empty window shows up when I launch software-properties-gtk, but sudo software-properties- gtk works ok. I renamed /etc/apt/sources.list.d so that presumably its contents won't be parsed. Below is my /etc/apt/sources.lst.
# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to # newer versions of the distribution. deb http://de.archive.ubuntu.com/ubuntu/ focal main restricted ## Major bug fix updates produced after the final release of the ## distribution. deb http://de.archive.ubuntu.com/ubuntu/ focal-updates main restricted ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team. Also, please note that software in universe WILL NOT receive any ## review or updates from the Ubuntu security team. deb http://de.archive.ubuntu.com/ubuntu/ focal universe deb http://de.archive.ubuntu.com/ubuntu/ focal-updates universe ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu ## team, and may not be under a free licence. Please satisfy yourself as to ## your rights to use the software. Also, please note that software in ## multiverse WILL NOT receive any review or updates from the Ubuntu ## security team. deb http://de.archive.ubuntu.com/ubuntu/ focal multiverse deb http://de.archive.ubuntu.com/ubuntu/ focal-updates multiverse ## N.B. software from this repository may not have been tested as ## extensively as that contained in the main release, although it includes ## newer versions of some applications which may provide useful features. ## Also, please note that software in backports WILL NOT receive any review ## or updates from the Ubuntu security team. deb http://de.archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse ## Uncomment the following two lines to add software from Canonical's ## 'partner' repository. ## This software is not part of Ubuntu, but is offered by Canonical and the ## respective vendors as a service to Ubuntu users. deb http://archive.canonical.com/ubuntu focal partner deb-src http://archive.canonical.com/ubuntu focal partner deb http://security.ubuntu.com/ubuntu focal-security main restricted deb http://security.ubuntu.com/ubuntu focal-security universe deb http://security.ubuntu.com/ubuntu focal-security multiverse -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1868501 Title: software-properties-gtk is blank when run as normal user. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/1868501/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
