I am getting this error when running sudo apt-get update
sudo apt-get update
Get:1 https://download.docker.com/linux/ubuntu bionic InRelease [64.4 kB]
Hit:2 https://deb.nodesource.com/node_16.x bionic InRelease
Get:3 https://dl.yarnpkg.com/debian stable InRelease [17.1 kB]
Hit:4 http://dl.google.com/linux/chrome/deb stable InRelease
Hit:5 https://repo.skype.com/deb stable InRelease
Hit:6 http://in.archive.ubuntu.com/ubuntu bionic InRelease
Hit:7 http://ppa.launchpad.net/deadsnakes/ppa/ubuntu bionic InRelease
Get:8 https://packages.microsoft.com/repos/ms-teams stable InRelease [5,931 B]
Hit:9 http://in.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:10 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:11 http://in.archive.ubuntu.com/ubuntu bionic-backports InRelease
Hit:12 http://ppa.launchpad.net/maarten-baert/simplescreenrecorder/ubuntu bionic InRelease
Hit:13 http://apt.postgresql.org/pub/repos/apt bionic-pgdg InRelease
Hit:14 https://download.sublimetext.com apt/stable/ InRelease
Hit:15 https://packages.redis.io/deb bionic InRelease
Hit:16 http://ppa.launchpad.net/nilarimogard/webupd8/ubuntu bionic InRelease
Hit:17 http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu bionic InRelease
Hit:18 https://repo.fortinet.com/repo/6.4/ubuntu /bionic InRelease
Err:18 https://repo.fortinet.com/repo/6.4/ubuntu /bionic InRelease
The following signatures were invalid: EXPKEYSIG 18AC26395E54716D Fortinet\FortiClient (Fortinet FortiClient DEB Package Signing) <support@fortinet.com>
Fetched 87.5 kB in 2s (36.1 kB/s)
Reading package lists... Done
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://repo.fortinet.com/repo/6.4/ubuntu /bionic InRelease: The following signatures were invalid: EXPKEYSIG 18AC26395E54716D Fortinet\FortiClient (Fortinet FortiClient DEB Package Signing) <support@fortinet.com>
W: Failed to fetch https://repo.fortinet.com/repo/6.4/ubuntu/dists//bionic/InRelease The following signatures were invalid: EXPKEYSIG 18AC26395E54716D Fortinet\FortiClient (Fortinet FortiClient DEB Package Signing) <support@fortinet.com>
W: Some index files failed to download. They have been ignored, or old ones used instead.
I have even tried to use the following command but no luck.Any help is appreciated
sudo apt autoremove --purge forticlient
Ubuntu - 18.04
