Installation with iso Installer not working due to lack of GPG keys

[jhamann]

Hello,
I have recently tried to install 3CX into a fresh VM using the latest iso file. However, during the installation process I get an error because "the public key is not available". I tried the same installation with the same iso one week ago and it worked fine then.
Please find attached the screenshots of the sources.list.d/ and the output of apt update.

 

[AWS2P]

Did you used a recent iso file or an old one previously DL?
Your screen copy are about Stretch and not Buster

 

[jhamann]

I used the iso from this website: https://www.3cx.com/phone-system/download-links/
Downloaded it freshly on Friday. But I can do it again.

 

[jhamann]

Ok I figured it out. There was a faulty Squid Cache that returned 0 bytes when asked for the GPG key instead of returning the actual key. Sorry for bothering.