How to fix apt update EXPKEYSIG 1F3045A5DF7587C3

Problem:

When running sudo apt update you see the following error message:

Err:14 https://repo.skype.com/deb stable InRelease
  The following signatures were invalid: EXPKEYSIG 1F3045A5DF7587C3 Skype Linux Client Repository <[email protected]>

Solution

Delete and re-add the skype key using using

sudo apt-key del 1F3045A5DF7587C3
curl https://repo.skype.com/data/SKYPE-GPG-KEY | sudo apt-key add -

After that, the error should be fixed and you can run

sudo apt update

again.