我一直尝试在我的 ubuntu 18.04 VPS 上安装 mariadb-server 和 mariadb-client，但是当我运行 apt install -y mariadb-server mariadb-client 时它返回：
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
mariadb-client : Depends: mariadb-client-10.8 (>= 1:10.8.3+maria~bionic) but it is not going to be installed
mariadb-server : Depends: mariadb-server-10.8 (>= 1:10.8.3+maria~bionic) but it is not going to be installed
N: Ignoring file 'mariadb.list.old_3' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'mariadb.list.old_2' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'mariadb.list.old_1' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
E: Unable to correct problems, you have held broken packages.
我已经寻找了两个多小时，却找不到任何有效的解决方案。
有人可以帮忙吗？
谢谢！