after upgrading to version 9.1.2053.0 the french language has disappeared from the available languages of the interface. Before I was using version 9.0.1708.0 and french language was available for UI.
Close and uninstall eM Client, making sure NOT to delete the database folder when asked. That will ensure all your data and settings are there later.
If it exists, delete the C:\Program Files (x86)\eM Client folder.
Download and install the latest version from here: https://www.emclient.com/dist/v9.1.2053/setup.msi
Restart eM Client.
Thanks. I just have downloaded and executed the specified file (https://www.emclient.com/dist/v9.1.2053/setup.msi) and do a Repair without uninstalling before, and it is now OK . I have the french language for UI