unable to update - repository is not updated, invalid signatures

I am unable to update libs and dependencies

The repository is not updated and the previous index files will be used. GPG error: all In Release: The following signatures were invalid: EXPKEYSIG 18DF3741CDFFDE29 philandro Software GmbH <>
W: Failed to fetch The following signatures were invalid: EXPKEYSIG 18DF3741CDFFDE29 philandro Software GmbH <>

getting the above error help needed, thanks in advance

1 Answer

You have to follow their documentation from .

To (re)add GPG key open terminal and execute:

wget -qO - | sudo apt-key add -

then update package lists by

sudo apt-get update