Seems there is something broken with your apt list files. You can try to reinitialize them. Edit this two files:

/etc/apt/sources.list
/etc/apt/sources.list.d/raspi.list

Note what lines does not have a # at first character. Set it and save the files. The do:

rpi ~$ sudo apt update

Because there are no entries in sources.list and raspi.list (they are all commented) all list files for the repositories will be removed. Now edit the two files again and remove the # you have set, but only that. Now do:

rpi ~$ sudo apt update
rpi ~$ sudo apt full-upgrade

Don't know if it helps but it is worth a try.

Seems there is something broken with your apt list files. You can try to reinitialize them. Edit this two files:

/etc/apt/sources.list
/etc/apt/sources.list.d/raspi.list

Note what lines does not have a # at first character. Set it and save the files. Then do:

rpi ~$ sudo apt update

Because there are no entries in sources.list and raspi.list (they are all commented), all list files for the repositories will be removed. Now edit the two files again and remove the # you have set, but only that. Now do:

rpi ~$ sudo apt update
rpi ~$ sudo apt full-upgrade

Don't know if that helps but it is worth a try.