Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: E

[setycz]

Dear support,

since 20th May we have started to encounter random failures when invoking `DropboxClient.Files.ListFolderAsync` function, see the following stacktrace:

Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: E. Path '', line 0, position 0.
at Newtonsoft.Json.JsonTextReader.ParseValue()
at Dropbox.Api.Stone.JsonReader.Read[T](String json, IDecoder`1 decoder)
at Dropbox.Api.DropboxRequestHandler.<RequestJsonString>d__20.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at Dropbox.Api.DropboxRequestHandler.<RequestJsonStringWithRetry>d__18.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at Dropbox.Api.DropboxRequestHandler.<Dropbox-Api-Stone-ITransport-SendRpcRequestAsync>d__12`3.MoveNext()
--- End of stack trace from previous location where exception was thrown ---

One day the same code with the same storage works and the other it does not. This and the fact that the JSON response from DropBox seems to be invalid indicates that the issue might be with DropBox API it-self. The issue seems to be appearing more often lately. 

Our application is .NET Framework 4.8 and using Dropbox.Api 6.30.0.

Were there any recent breaking changes? Could you check the API on your side? Or recommend any actions we can take?

[Greg-DB]

I see some of your messages got caught by an automated spam filter. I've recovered them.

Anyway, thanks for the additional information; that's helpful. We'll look into it.

[Greg-DB]

I've tried your sample code and the issue doesn't reproduce for me, so it may be specific to some aspect of your environment or account.

That being the case, to help us track down these specific failures, please open an API ticket here and share the following:

• Have you made any modifications to the Dropbox SDK? If so, please share them.
• Please include several 'X-Dropbox-Request-Id' response header values for several responses with the error shown here.
• Please include the IP address used to make the requests that resulted in the errors identified in the previous item.

Thanks in advance and apologies for the bother!

[setycz]

Hello Greg-DB,

I have reproduced the issue today and submitted the request as you suggested. It was actually pretty hard to reproduce it today, it took 1432 requests. I'll also post the data you asked for here:

• Have you made any modifications to the Dropbox SDK? If so, please share them.
  • no changes
• Please include several 'X-Dropbox-Request-Id' response header values for several responses with the error shown here.
  • [X-Dropbox-Request-Id]=[5540b28dca5e40c1aa5ecde595c983a5]
• Please include the IP address used to make the requests that resulted in the errors identified in the previous item.
  • (I won't rather post it here, but it is included in the ticket :D)

Thank you for your help.

[Greg-DB]

Thanks for submitting that. The team will review your ticket and follow up with you there.

[STEALTHbits]

@Greg-DB @setycz I am wondering if something was fixed, I was seeing this error back in late June/early July and handled the exception itself. However, as of July 21st I have not seen it.  For me this error was occurring after an hour runtime of consistent calls to GetSharedFile/FolderMembers

[Greg-DB]

@STEALTHbits Yes, the team worked on tracking this down and resolving it.