The repository 'https://.../Debian_9.0 Release' does not have a Release file.

aro

I’m trying to install Kopano on a fresh Debian 9.8.0. When I add the kopano.list to the /sources.list.d/ and run apt-get udate, I get the following output:

[...]
Ign:21 https://download.kopano.io/supported/webapp:/final/Debian_9.0  Translation-en
Fehl:11 https://download.kopano.io/supported/core:/final/Debian_9.0  Packages
[...]
Ign:15 https://download.kopano.io/supported/core:/final/Debian_9.0  Translation-de_DE
Fehl:17 https://download.kopano.io/supported/webapp:/final/Debian_9.0  Packages
[...]
Ign:21 https://download.kopano.io/supported/webapp:/final/Debian_9.0  Translation-en
Paketlisten werden gelesen... Fertig
W: The repository 'https://download.kopano.io/supported/core:/final/Debian_9.0  Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: The repository 'https://download.kopano.io/supported/webapp:/final/Debian_9.0  Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
E: Fehlschlag beim Holen von https://download.kopano.io/supported/core:/final/Debian_9.0/Packages  
E: Fehlschlag beim Holen von https://download.kopano.io/supported/webapp:/final/Debian_9.0/Packages  
E: Einige Indexdateien konnten nicht heruntergeladen werden. Sie wurden ignoriert oder alte an ihrer Stelle benutzt.

The kopano.list has been generated using the Portal-Wizard:

deb https://serial:SERIAL@download.kopano.io/supported/webapp:/final/Debian_9.0/ / 
deb https://serial:SERIAL@download.kopano.io/supported/core:/final/Debian_9.0/ /

apt-transport-https (version 1.4.9) is installed, the Release.key from the kopano-Repo has been imported:

# apt-key list
/etc/apt/trusted.gpg
--------------------
pub   rsa4096 2016-04-29 [SC] [expires: 2021-04-28]
      DF37 89BC EB21 99DE 08D7  43A5 5CB2 7E13 58E2 F2A7
uid           [ unknown] Kopano Development <development@kopano.io>
sub   rsa4096 2016-04-29 [E] [expires: 2021-04-28]

Installing Software from the Debian-Repos works, also as from the Z-Push-Repo.
Logging in to the Downloadserver with Firefox and my credentials, I can navigate the “supported”-folder-structure and download the .deb-Files manually.
Adding [trusted=yes] or [allow-insecure=yes] to the kopano.list-entries does not do the trick.
Does anyone have an idea why I’m stuck?

aro

Well, figured it out myself, here’s how to solve it, if someone rans into it, too:

First, check the https-feature of apt with debug: option:

> apt-get update -o Debug::Acquire::https=1

In my case, there have been errors, like “no access to ca_certificates.crt” and so on.
The read/write-permissions of /etc/ssl/certs/ were set propperly, so i did reinstall the certificate_ca and apt-transport-https:

> apt install ca-certificates apt-transport-https

Verifying, with the debug outpout again to see if it got fixed:

> apt-get update -o Debug::Acquire::https=1

The errors are gone, doing an apt-get update

> apt-get update
[...]
OK:7 http://ftp.de.debian.org/debian stretch Release 
Ign:8 https://download.kopano.io/supported/core:/final/Debian_9.0  InRelease
Ign:2 https://attic.owncloud.com/org/download/repositories/production/Debian_9.0  InRelease
OK:9 http://download.owncloud.org/download/repositories/production/Debian_9.0  Release
Ign:10 https://download.kopano.io/supported/webapp:/final/Debian_9.0  InRelease
OK:11 https://download.kopano.io/supported/core:/final/Debian_9.0  Release
OK:12 https://download.kopano.io/supported/webapp:/final/Debian_9.0  Release
Paketlisten werden gelesen... Fertig