Installing Feed the Beast (Direwolf20 1.18.2) not possible

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OS Name/Version: Debian 9

Product Name/Version: (Always use the full version number - not ‘Latest’)

Problem Description: When trying to install “Feed the Beast (new source)” as Server Type and trying to update the following error message appears

Download / Update failed : Couldn't determine the URL to fetch an update from. You may need to install this server type manually.

Steps to reproduce:


Actions taken to resolve so far: Trying to google for a workaround

Unable to reproduce

Is this a fresh instance?

Yes, absolute.

When I go to Servertype → FTB (New Source)

I get this

The Modpack List is empty

Can you post the instance logs?

It kinda got fixed after I created a new instance, so it seemed to be a temporary issue.
Sorry for the delayed update.

But now i am encountering the propblem on how to import my preexisting world to my instance/server.
When I manually copy it via sftp and click on “search for new worlds” nothing happens.