Multiple "failed to fetch" on Ubuntu 20.04LT machine

Question

I tried to update my Ubuntu 20.04LT desktop this AM. Up until yesterday this was working in a straight forward way. Today, a whole series of fetches failed. (See below.) Among them one failure resulted in what I think is the inability to use the Invidia graphics card interface, with the impact that I get a vanilla 800 x 600 pixel screen rather than my usual 1920 x 1080 resolution. How do I fix this problem of not being able to fetch all these packages, and in particular, fixing my screen resolution problem? I am downloading from the Ubuntu Main Server and have run sudo apt update to update my sources.

Thanks in advance for any help or suggestions. Larry Hunsicker

error output from sudo apt upgrade: E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libd/libdrm/libdrm2_2.4.102-1ubuntu1~20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libd/libdrm/libdrm-intel1_2.4.102-1ubuntu1~20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libd/libdrm/libdrm-radeon1_2.4.102-1ubuntu1~20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libg/libglvnd/libopengl0_1.3.2-1~ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libg/libglvnd/libgl-dev_1.3.2-1~ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/m/mesa/libegl-mesa0_20.2.6-0ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/x/xorg-server/xserver-xorg-core_1.20.9-2ubuntu1.1~20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/m/mesa/libgl1-mesa-dri_20.2.6-0ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/m/mesa/libglapi-mesa_20.2.6-0ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libg/libglvnd/libgles-dev_1.3.2-1~ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libg/libglvnd/libgles2_1.3.2-1~ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libg/libglvnd/libglvnd-dev_1.3.2-1~ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/libg/libglvnd/libglvnd0_1.3.2-1~ubuntu0.20.04.1_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/l/linux-hwe-5.8/linux-modules-5.8.0-34-generic_5.8.0-34.37~20.04.2_amd64.deb 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/l/linux-hwe-5.8/linux-modules-extra-5.8.0-34-generic_5.8.0-34.37~20.04.2_amd64.deb 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/l/linux-meta-hwe-5.8/linux-image-generic-hwe-20.04_5.8.0.34.37~20.04.20_amd64.deb 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/pool/main/l/linux-hwe-5.8/linux-headers-5.8.0-34-generic_5.8.0-34.37~20.04.2_amd64.deb 400 Bad Request [IP: 91.189.91.38 80]

error output from sudo apt update: E: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/main/dep11/icons-64x64.tar 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/focal/main/dep11/icons-64x64.tar 400 Bad Request [IP: 91.189.91.39 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/focal-updates/main/dep11/icons-64x64.tar 400 Bad Request [IP: 91.189.91.38 80] E: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/focal-backports/main/cnf/Commands-amd64 400 Bad Request [IP: 91.189.91.38 80] E: Some index files failed to download. They have been ignored, or old ones used instead.

Answer 1

等待大神答复