Error: Dropbox-API: (6) couldn’t resolve content.dropboxapi.com
BackWPup says ERROR: Dropbox-API: (6)? In case you chose Dropbox as backup target, you might get the following error message when uploading the backup to Dropbox:
ERROR: Dropbox API: (6) Couldn't resolve host 'content.dropboxapi.com'
According to Dropbox this is a DNS error – read: https://www.dropboxforum.com/t5/API-support/Error-Dropbox-API-6/m-p/193010. Due to that, the domain content.dropboxapi.com cannot be resolved correctly.
In this case you should contact the hoster as the network and internet connection of the web server needs to be checked. On the other hand, the error might have occured due to a temporary internet outage while uploading the file.
In case the upload to Dropbox displays this error message after a couple of tries, you should definitely contact the hoster.