Text "login_required.welcome_message": The following interpolation key(s) are missing: "title"

[gerhard (Gerhard Schlager)]

It’s the forum title. So, replacing “plentymarkets Forum” in the first line with %{title} should make it work.

# [Willkommen im %{title}](#welcome)

(Oh, and you probably want a space after # otherwise it won’t be formatted as heading.)