"source toaster start" fails to start with when using Django 1.8 which is the current version in bitbake/toaster-requirements.txt I manually updated toaster-requirements.txt Django>2.2,<2.3 beautifulsoup4>=4.4.0 pytz Which appears to be working as expected.
This commit seems to be the root cause of this in Dunfell: https://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/bitbake/lib/toaster/toastermain/urls.py?h=dunfell&id=4dabdbe11ddc47a885c7f8cc6b3f26439d40d77c I backed out the change to line 72 and toaster starts.
toaster-requirements.txt was updated to require Django >2.2<2.3 (to intentionally pin it to the 2.2.x LTS version until 3.2.x LTS is available in April 2021) Fixed in Dunfell 3.1.1: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?h=dunfell&id=5890b72bd68673738b38e67019dadcbcaf643ed8 And in current tree: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=68e76d0d4b266719922b2cea5508acf4716b92cb