Update / Upgrade not Possible / Unable to obtain the latest version of Parallels Ins.

[WebMe1ster]

Possible interference of command line update with autoinstaller update?

Unable to obtain the latest version of Parallels Installer: The required version '3.16.3' was not found on the server. This could happen because of configuration error at the download site. Failed to download the package https://autoinstall.plesk.com/Parallels_Installer/parallels_installer_Debian_7_x86_64.md5sum: The requested URL returned error: 404

Hi! I get the idenical error message on one of my three servers. All three servers got identical hardware and are idetically configuered using Debian 7.6 from my provider. While two servers updated without any problem to Version 12.0.18, one server got stuck somehow and still is in "Parallels Plesk Panel v11.5.30_build115130819.13 os_Debian 7.0".
I believe the problem showed up during an update that I initiated in the shell using "apt-get update; apt-get upgrade;" or "apt-get update; apt-get dist-upgrade;" - I don't remember exactly.
My guess: The update via command line somehow interfered with an automatic update in Plesk?
Any solution to this?