Ubuntu20.04安装plymouth遇到错误/var/cache/apt/archives/libpng12-0_1.2.54-1ubuntu1.1_amd64.deb

详情如下： 

The following package was automatically installed and is no longer required:
  libplymouth5
Use 'sudo apt autoremove' to remove it.
The following NEW packages will be installed:
  libpng12-0
0 upgraded, 1 newly installed, 0 to remove and 1 not upgraded.
3 not fully installed or removed.
Need to get 0 B/116 kB of archives.
After this operation, 285 kB of additional disk space will be used.
(Reading database ... 174419 files and directories currently installed.)
Preparing to unpack .../libpng12-0_1.2.54-1ubuntu1.1_amd64.deb ...
Unpacking libpng12-0:amd64 (1.2.54-1ubuntu1.1) ...
dpkg: error processing archive /var/cache/apt/archives/libpng12-0_1.2.54-1ubuntu1.1_amd64.deb (--unpack):
 unable to install new version of '/lib/x86_64-linux-gnu/libpng12.so.0': No such file or directory
No apport report written because the error message indicates an issue on the local system
         Errors were encountered while processing:
 /var/cache/apt/archives/libpng12-0_1.2.54-1ubuntu1.1_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

试了网上很多种方式，都不行。

参考链接：

dpkg: 处理归档 /var/cache/apt/archives/libpng12-0_1.2.54-1ubuntu1.1_amd64.deb (--unpack)时出错： 无法安装 /lib/_shuaibi.1的博客-CSDN博客问题：在ubuntu19.04使用sudo apt-get update 提示标题内容。原因：Ubuntu 14以上就已经不再支持libpng12，然而有些软件又依赖于libpng12。使用sudo apt install xxx提示下列软件包有未满足的依赖关系：openjdk-9-jre : 依赖: libpng12-0 (>= 1.2.13-4) 但是它将不会被安装。因此得知o...https://blog.csdn.net/sinat_37064286/article/details/102943997

Fix libpng12-0 Missing In Ubuntu 18.04, 19.10, 20.04 Or 20.10 - Linux Uprising BlogIn this article you'll find a very easy to apply fix that will allow installing and running applications that depend on libpng12-0 in Ubuntu 18.04 LTS or Linux Mint 19.https://www.linuxuprising.com/2018/05/fix-libpng12-0-missing-in-ubuntu-1804.html 

 上面的链接是很多方法的集合了，但是我的问题还是没有解决。后来我找了这个包的地址：

Index of /linuxuprising/libpng12/ubuntu/pool/main/libp/libpnghttp://ppa.launchpad.net/linuxuprising/libpng12/ubuntu/pool/main/libp/libpng/

链接里下面框出来的下载，一个一个试，我是第一个就OK了，祝大家好运！