Update error
 

Keep getting this error. Any help please.

W: GPG error: http://download.opensuse.org/reposit.../stevenpusser/
xUBUNTU_16.04 Release: The following signatures could'nt be verified
because the publc key is not available: no_pubkey 0FAD31CA8719FCE4
W: Te repositories http://download.opensuse.org/repositories/home/
stevenpusser/xubuntu_16.04 release is not signed.

you do know that this repo is basically a personal one that others can choose to also use
and there really is not much in it

firejail , fossamail, palemoon

all of these should be in the debian repos

Open update manager and uncheck this repo. Now try to update again, you should not get the same error again.