[Solved] E: Unable to correct problems, you have held broken packages.

$ apt-get install mariadb-server
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-server : Depends: mariadb-server-10.5 (>= 1:10.5.13+maria~focal) but it is not going to be installed
N: Ignoring file 'maria.key' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
N: Ignoring file 'apt-key' in directory '/etc/apt/sources.list.d/' as it has no filename extension
E: Unable to correct problems, you have held broken packages

Install aptitude

sudo apt-get install aptitude

Use aptitude to install packages

sudo aptitude install mariadb-server

Use the Yes or No options to find the right combinations of the packages and set them up.

Comment if you know any other efficient solutions.
thanks.