Problem with nextcloudcmd


I had a server with a lot of photo (4Go). I had an other server with nextcloud. I want to make my photo on nextcloud, so synchronise the two server.

My first server is on Debian Stable, I installed the package nextcloud-desktop-cmd. I read doc and write this command:
$ nextcloudcmd -u Gysanineth -p *** testnextcloud
And I have this error:
02-25 10:11:59:812 [ fatal default ]: Cannot load system exclude list or list supplied via --exclude
The folder “testnextcloud” exist.

What do I make wrong ?