This is a spin-off of T6014: Failed to search on certificate server. The error returned was: Syntax error in URI..
For example "email@example.com". But what I meant is that code handling WKD errors that show an information to the user should not exist. All WKD lookup errors in Search should be silently discarded. Because the user does not know that he is performing a WKD search so she should not be informed about errors in that.
Looking up "firstname.lastname@example.org" in Kleopatra results in a "General error" being reported.