This’ll be a short post, more for my own reference than anything else!
When running sudo apt update, I got the following error:
Err:8 https://dl.yarnpkg.com/debian stable InRelease
The following signatures were invalid: EXPKEYSIG 23E7166788B63E1E Yarn Packaging <yarn@dan.cx>
[...]
W: An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: https://dl.yarnpkg.com/debian stable InRelease: The following signatures were invalid: EXPKEYSIG 23E7166788B63E1E Yarn Packaging <yarn@dan.cx>
W: Failed to fetch https://dl.yarnpkg.com/debian/dists/stable/InRelease The following signatures were invalid: EXPKEYSIG 23E7166788B63E1E Yarn Packaging <yarn@dan.cx>
W: Some index files failed to download. They have been ignored, or old ones used instead.
Googling this returns a mixture of results and fixes, but the one I’ve found works the majority of the time is:
sudo apt-key adv --refresh-keys --keyserver keyserver.ubuntu.com
Running sudo apt update again then works — yay! 🎉