I have recently upgraded to version 4.2 and discovered that Kleopatra has a problem related to keyservers configuration.
Settings -> Configure Kleopatra -> Directory services
I manually added several HKP keyservers (the same as I use in my Enigmail).
The next time I opened this configuration I saw an empty list.
Not totally empty, there were several entries, but without any text.
{F6072709}
I can press "Edit" on such an entry, which opens an edit window with an empty serverl URL field.
The connection security radio box however seems to have the value I set when adding.
{F6072718}
Note: tested on a Win7 VM.
As such I am uncertain what keyserver(s) Kleopatra would use when searching or uploading keys.
Apparently a key upload works though.
P.S.
why the keyserver suggestion is specifically from ubuntu?