Weird APT/Buster issues when Checking for updates

[wbk]

@brimwats

When I check for updates I get this:

Fetching available upgrades for system packages...
W: An error occurred during the signature verification. 
... 
The following signatures were invalid: EXPKEYSIG 

The error looked familiar, I thought I’d look up the steps to resolve it. The first result I clicked was a previous post of yours

You could try deleting the expired key and fetching a new one :

$ sudo apt-key del 39217939ED3D07DB
$ sudo curl -sSL -o /etc/apt/trusted.gpg.d/php.gpg https://repo.delellis.com.ar/repo.gpg.key