Hello,
I'm a collegue of François who have openned this post. We have now solved the problem.
The solution was to completely re-install :
Retrieve old key from productive system. -> C:\Program Files\NetApp\WFA\bin>wfa.cmd -key
Backup the DB
uninstall completely the product
Delete the folder netapp in \program files
reboot the server
install WFA 3.1
Set the key -> C:\Program Files\NetApp\WFA\bin>wfa.cmd -key=ZEd+3UHR8IeXKr6XTOFQvQ==
restore the DB
Jerome