How to get rid from a message

Hi,

Each time I synchronize DTTG with dropbox, I get the following message :

“création du dossier de base de données impossible, le chemin existe déjà” (Localized in French). Translation in English : Unable to create the database folder, the path already exists
What’s the meaning of this message ?
How can I get rid of it ?

Thanks in advance

François

Does it work after cleaning this database from the sync store via the contextual menu in Preferences > Sync?