I solved the problem using the following answer from stackoverflow:
1.Stop the mongod process by issuing the following command:-
sudo service mongod stop
2.Remove any MongoDB packages that you had previously installed:-
sudo apt-get purge mongodb-org*
3.Remove MongoDB databases and log files:-
sudo rm -r /var/log/mongodb
sudo rm -r /var/lib/mongodb
4.Then reinstall mangodb 4.4.8
5.Import the public key used by the package management system:-
wget -qO - https://www.mongodb.org/static/pgp/server-4.4.asc | sudo apt-key add -
6.The following instruction is for Ubuntu 20.04 (Focal):-
echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu focal/mongodb-org/4.4 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-4.4.list
7.Update Apt
sudo apt-get update
8.Install mongodb
sudo apt-get install mongodb-org=4.4.8 mongodb-org-server=4.4.8 mongodb-org-shell=4.4.8 mongodb-org-mongos=4.4.8 mongodb-org-tools=4.4.8
9.Use mongod --version to check its succesfully installed
10.If u encounter any error while using mongod
sudo mkdir /data
cd /data
sudo mkdir db
sudo pkill -f mongod
11.Then use sudo mongod command.
by Abdul Wahhab
source: https://stackoverflow.com/questions/68742794/mongodb-failed-result-core-dump