Autofocus warnings messages

Hello

Since from the beginning of the session, I get several auto-focus related warning messages, like these

[22/03/2018 00:43:29][Warning] (NGC3189) Cannot find focus point, assuming focus is outward, adjusting smart focus range…
or this
[22/03/2018 00:44:53][Warning] (NGC3189) Cannot find focus point (asymmetrical slopes), defaulting to lowest weighted HFR method…
or this
[22/03/2018 00:11:36][Warning] (NGC3189) Warning! Auto focus validation frame HFR (1,12) might be out of tolerance with respect to expected HFR (1,06 or lower).

I have not found and I don’t know that these messages will mean and how I can tweak that.

Thank you for your help.

Claude
(France)