Thank you, FLOOD, for your help.
First I'm under Windows 10
Second My Lastpass version compatible, is v4.31.1
Third What I do:
I select More Options in the left navigation.
I Go to Advanced > Export
I right click > Save as... LastPass CSV File.
I Enter a File name as Lastpass-export.csv instead of My LastPass Vault.html proposed by LastPass
With KPM I go to Parameters > Import/Export
In import data from a password manager > Import
I select Lastpass-export.csv > Choose
The résult of KPM is : Data import is not complete. Failed to import and passwords. An error occurred during the import.:persevere: