i read the instructions that said:
Reverting to a previous version
You can install a previous calibre release, like this:
sudo -v && sudo apt-get remove calibre && wget -nv -O-
https://download.calibre-ebook.com/linux-installer.sh | sudo sh /dev/stdin version=3.29.0
Change 3.48.0 above to whatever version you want installed.
well, it removed the current version of Calibre ok, but then it went on to say:
Error:
https://code.calibre-ebook.com/signa..._64.txz.sha512 returned an unsupported http response code: 404 (Not Found
so this last part in invalid. how do i install version 3.29 ?