尝试运行从 Epson 网站下载的打印机实用程序时，出现以下错误：
epson-printer-utility: error while loading shared libraries: libQtCore.so.4: cannot open shared object file: No such file or directory
我认为这是因为 QT4 库没有安装在 Ubuntu 20.04 LTS 上。它似乎不再可供安装。
我在谷歌上搜索并尝试通过各种方式安装各种 QT4 库，但没有成功。例如：
$ sudo apt-get install qt4-default
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package qt4-default is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'qt4-default' has …