A new Dropbox paclet has been pushed live which will resolve this issue. Basically the issue was due to Dropbox has stopped version 1 api support. More information at https://blogs.dropbox.com/developers/2017/06/updated-api-v1-deprecation-timeline/
The new paclet supports v2 apis which are new and faster.
In[3]:= PacletUpdate["ServiceConnection_Dropbox"]
Out[3]= PacletManager`Paclet[
"Name" -> "ServiceConnection_Dropbox", "Version" -> "11.2.0",
"MathematicaVersion" -> "11.0+",
"Extensions" -> {{
"Kernel", "Root" -> "Kernel",
"Context" -> {"Dropbox`", " DropboxLoad`"}}, {
"Documentation", "MainPage" -> "ReferencePages/Symbols/Dropbox",
"Language" -> "English"}},
"Location" -> "/Users/damanjits/Library/Mathematica/Paclets/\
Repository/ServiceConnection_Dropbox-11.2.0"]
In[4]:= Quit
In[1]:= RebuildPacletData[]
In[2]:= dropbox = ServiceConnect["Dropbox"]
Out[2]= ServiceObject["Dropbox",
"ID" -> "connection-cce5eb7df530d3b6cb6d12ac438d97c8"]
In[4]:= dropbox["UserData"]
Out[4]= <|"ReferralLink" -> "https://db.tt/G06FmxYB",
"Disabled" -> False, "IsPaired" -> False,
"Email" -> "testwolfram1@gmail.com",
"AccountID" -> "dbid:AAALg-wp1VzCpe-BncerqAd442vQb9PkfHo",
"Name" -> {"FamiliarName" -> "Test", "GivenName" -> "Test",
"AbbreviatedName" -> "TW", "Surname" -> "Wolfram",
"DisplayName" -> "Test Wolfram"}, "EmailVerified" -> True,
"Country" -> "US", "AccountType" -> {"Tag" -> "basic"},
"Locale" -> "en"|>
In[5]:= dropbox["FileNames", "Path" -> "/WolframGraphics"]
Out[5]= Dataset[ <> ]
In[7]:= dropbox[
"DirectoryTreePlot", {"Path" -> "/", "Recursive" -> True}] // Head
Out[7]= Graphics
Notice the change in parameters of DirectoryTreePlot
, "Root" parameter is no longer used in all the requests. Instead File/Directory path should start with '/'. These minor documentation tweaks will be available soon in online documentation.