1. texlive after a new version, does not support a direct upgrade, you need to download and install. After the installation is recommended to uninstall the old version, or there will be some cases are still looking for the path of the old version. And the old version of tex live manager can not update the library.
Live manager 2. texlive with a good use when installing the missing bag, but sometimes can not find the problem occurs, then you can manually:
To https://www.ctan.org/pkg/
in the download package, unzip into a folder into C: \ texlive \ 2018 \ texmf -dist \ tex \ latex in,
and then execute the command: texhash
If the file folder is .ins file, it first needs to perform latex xx.ins command to generate .sty files and sty into the directory.