When doing sudo apt update I get the warnings shown below. This is very annoying and somewhat alarming to see, but why does it even happen?
W: Skipping acquire of configured file 'partner/binary-amd64/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-i386/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en_GB' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/Components-amd64.yml' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-48x48.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-64x64.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-i386' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/cnf/Commands-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-i386/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-amd64/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en_GB' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/Components-amd64.yml' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-48x48.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-64x64.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-i386' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/cnf/Commands-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-updates InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-i386/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-amd64/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en_GB' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/Components-amd64.yml' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-48x48.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-64x64.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-i386' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/cnf/Commands-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-backports InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-amd64/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-i386/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en_GB' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/Components-amd64.yml' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-48x48.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-64x64.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-i386' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/cnf/Commands-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-security InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-amd64/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/binary-i386/Packages' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/i18n/Translation-en_GB' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/Components-amd64.yml' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-48x48.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/dep11/icons-64x64.tar' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-i386' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/Contents-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?) W: Skipping acquire of configured file 'partner/cnf/Commands-amd64' as repository 'http://gb.archive.ubuntu.com/ubuntu bionic-proposed InRelease' doesn't have the component 'partner' (component misspelt in sources.list?)
It's been awhile since I used Ubuntu (last one I used was 14.04) so not sure if this will work anymore.
Go to settings and choose system, select update server on US or UK and click check updates (in other words, use the non-console way of retrieving updates).
If that won't work, then it's big ouch time. It looks like the components might be misspelt in sources.list or their partner is missing from there which means you have to check the sources.list if changeing the update server won't fix it automatically.