apt update in WSL fails: Failed to fetch ... no such file or directory

I already updated WSL itself (as Administrator)

> wsl --set-version ubuntu-20.04 2> wsl --update

Which worked but still did not solve my problem inside the WSL Ubuntu 20.04.

$ sudo apt updateReading package lists... Error!E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_main_binary-amd64_Packages.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_main_binary-amd64_Packages -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_main_binary-amd64_Packages).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_main_i18n_Translation-en.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_main_i18n_Translation-en -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_main_i18n_Translation-en).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_main_cnf_Commands-amd64.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_main_cnf_Commands-amd64 -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_main_cnf_Commands-amd64).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_restricted_binary-amd64_Packages.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_restricted_binary-amd64_Packages -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_restricted_binary-amd64_Packages).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_restricted_i18n_Translation-en.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_restricted_i18n_Translation-en -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_restricted_i18n_Translation-en).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_restricted_cnf_Commands-amd64.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_restricted_cnf_Commands-amd64 -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_restricted_cnf_Commands-amd64).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_universe_binary-amd64_Packages.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_universe_binary-amd64_Packages -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_universe_binary-amd64_Packages).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_universe_i18n_Translation-en.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_universe_i18n_Translation-en -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_universe_i18n_Translation-en).E: Failed to fetch store:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_universe_cnf_Commands-amd64.xz  rename failed, No such file or directory (/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_focal_universe_cnf_Commands-amd64 -> /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_focal_universe_cnf_Commands-amd64)....E: Some index files failed to download. They have been ignored, or old ones used instead.E: Problem renaming the file /var/cache/apt/srcpkgcache.bin.OL2UsH to /var/cache/apt/srcpkgcache.bin - rename (22: Invalid argument)E: Problem renaming the file /var/cache/apt/pkgcache.bin.EdYnXG to /var/cache/apt/pkgcache.bin - rename (22: Invalid argument)W: You may want to run apt-get update to correct these problemsE: The package cache file is corrupted

sudo rm -rf /var/lib/apt/lists/* and sudo apt clean did not help, too. Here are my sources, all from /etc/apt/sources.list.

deb http://archive.ubuntu.com/ubuntu/ focal main restricteddeb http://archive.ubuntu.com/ubuntu/ focal-updates main restricteddeb http://archive.ubuntu.com/ubuntu/ focal universedeb http://archive.ubuntu.com/ubuntu/ focal-updates universedeb http://archive.ubuntu.com/ubuntu/ focal multiversedeb http://archive.ubuntu.com/ubuntu/ focal-updates multiversedeb http://archive.ubuntu.com/ubuntu/ focal-backports main restricted universe multiverse# deb http://archive.canonical.com/ubuntu focal partnerdeb http://security.ubuntu.com/ubuntu/ focal-security main restricteddeb http://security.ubuntu.com/ubuntu/ focal-security universedeb http://security.ubuntu.com/ubuntu/ focal-security multiverse

I don't know if this is WSL related or Ubuntu related, but I guess the first as I never had such problems on native Ubuntu.

I use WSL mostly as SSH and Git client.

Anybody knows whats wrong here?