Errors when trying to upgrade to Ubuntu 21.04 from 20.10

Whenever I try and run software updater I just get the error "Failed to download repository. information please check your internet connection." and whenever I run sudo apt update I get the error

Get:6 https://packages.riot.im/debian default InRelease [2,892 B]
Err:6 https://packages.riot.im/debian default InRelease
  The following signatures were invalid: EXPKEYSIG C2850B265AC085BD riot.im packages <[email protected]>
Reading package lists... Done
W: GPG error: https://packages.riot.im/debian default InRelease: The following signatures were invalid: EXPKEYSIG C2850B265AC085BD riot.im packages <[email protected]>
E: The repository 'https://packages.riot.im/debian default InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.`

You have to update repository GPG key by using command below

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com C2850B265AC085BD

wget -q -O - https://packages.riot.im/element-release-key.gpg | sudo apt-key add -
wget -q -O - https://packages.riot.im/element-release-key-2020.gpg | sudo apt-key add -
wget -q -O - https://packages.riot.im/riot-release-key.gpg | sudo apt-key add -

and then install all updates with new dependencies to your current system by

sudo apt-get update
sudo apt-get dist-upgrade