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otky's avatar
otky
Explorer | Level 4
5 years ago

The underlying connection was closed error.

Hi,   I'm using DropBox API v2 to get folders and files from user account. For that I'm using "files/list_folder", "files/list_folder/continue" endpoints and also I'm using recursive: true for ro...
Developers
otky's avatar
otky
Explorer | Level 4
5 years ago

Thanks for the quick response . I'm not using any sdk just I'm using c# HttpWebRequest with API endpoints.

Find the below endpoints and breif description of the code .

 

endpoint : https://api.dropbox.com/2/files/list_folder

and adding {"path":"","recursive":true} to request stream

headers: Dropbox-API-Select-User:{{userId}}


if response contains "has_more" then using the below endpoint


endpoint : https://api.dropbox.com/2/files/list_folder/continue
{cursor:cursorid} to request stream
headers: Dropbox-API-Select-User:{{userId}}


to download files I'm using
endpoint: https://api-content.dropbox.com/2/files/download
{"path":"rev:{revisionId}"}

 

 

 

Regarding the error messages after running for sometime(more than 1 day) I got "Unable to connect to the remote server , A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond" sometimes and "The underlying connection was closed: A connection that was expected to be kept alive was closed by the server." sometimes.

 

Thanks,

OTKY

Greg-DB's avatar
Greg-DB
Icon for Dropbox Community Moderator rankDropbox Community Moderator
5 years ago

Thanks for following up. It's not clear from this why this would be happening, but a few possibilities/other questions:

  • Is there anything on your network connection, such as a firewall, proxy, VPN, anti-virus, or other security software that may be interfering with your connection to api-content.dropbox.com?
  • When you say it's "running for sometime(more than 1 day)", do you mean the overall process, or an individual request? How long is an individual /2/files/download request taking before failing?
  • About what percent of your /2/files/download requests are failing?
  • When you say you have "when multiple colletions running at same time", do you mean you have more than one request to /2/files/download running simultaneously? If so, how many?
  • otky's avatar
    otky
    Explorer | Level 4
    5 years ago

    Hi,

    Please find my answers in Italic.

     

    • Is there anything on your network connection, such as a firewall, proxy, VPN, anti-virus, or other security software that may be interfering with your connection to api-content.dropbox.com?

    I'm not sure about these. But do these things cause the issue for accounts which have larger number of files?

     

    • When you say it's "running for sometime(more than 1 day)", do you mean the overall process, or an individual request? How long is an individual /2/files/download request taking before failing?

    Yes the overall process for downloading the files one by one from DropBox account.

     

    • About what percent of your /2/files/download requests are failing?

    Sometimes its failing at "/2/files/download" and sometimes its failing at "files/list_folder/continue" . But in both the cases its not failing immediately. 

     

    • When you say you have "when multiple colletions running at same time", do you mean you have more than one request to /2/files/download running simultaneously? If so, how many?

    Yes , 2-3 processes running simultaneously .Is there any chances of throttling here ? If there is a throttling issue , will all the processes running at that time will throw errors  and stop execution from then?

     

    Thanks,

    OTKY.

     

     

     

     

     

    • Greg-DB's avatar
      Greg-DB
      Icon for Dropbox Community Moderator rankDropbox Community Moderator
      5 years ago

      Things potentially interfering with your network connection wouldn't depend on how many files are in the connected account. I recommend checking for any such potential issues regardless of the file count.

       

      For reference, the Dropbox API does have a rate limiting system, but if it rejects any particular call, it would respond with an explicit error response, with a 429 status code. It would not just close the connection as you're seeing here, so that does not seem to be the issue. In any case, 2-3 simultaneous requests is not excessive and so we would not expect such activity to be rate limited.

       

      Also, since this is actually happening on both /2/files/download and /2/files/list_folder/continue (which use different hosts), it sounds like there's likely client-side issue here. We can't offer help with HttpWebRequest itself though, as that's not made by Dropbox.

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