Suggested articles cannot be opened

[Deleted user]

Hi, 

In the customer portal, I choose a request type and type a key word.

Suggested articles are presented but cannot be opened. I get the following error message:

I get this message with all request type.

However, if I type a keyword in the search field, without choosing a request type, suggested articles are presented and I can open then.

In Project settings, all Request form have the value Yes for Searck in KB.