Upgrade issues - Invalid file name extension

[tryckman]

I am trying to upgrade to 4.0 and when I run apt-get update I receive this error:

Ignoring file 'zabbix-release_4.0-2+bionic_all.deb' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension

Any ideas?

[tryckman]

Does anyone have ideas on this?