Forum Discussion

Explorer | Level 4

7 months ago

GET request to /files/download fails with "The network connection was lost"

Hi, Our app uses Dropbox's HTTP API to upload and download files. Since a few days ago, some of our app's requests are failing with "The network connection was lost". This issue was first reported...

API

Greg-DB

Dropbox Staff

7 months ago

While we can't offer insight on the client platforms/libraries in particular, this is the right place for help with the Dropbox API itself.

For reference, the Dropbox does use POST for all API calls by default, but "content-download" style endpoints, such as /2/files/download, do additionally support GET. And it's correct that the endpoint does not support POST requests with a non-empty body.

I just tried it out, and confirmed that the API is still allowing both GET and POST for this endpoint in my testing:

curl -v -X POST https://content.dropboxapi.com/2/files/download \
    --header "Authorization: Bearer <ACCESS_TOKEN>" \
    --header "Dropbox-API-Arg: {\"path\":\"/test.txt\"}" \
    --header "Content-Type: application/octet-stream"

> POST /2/files/download HTTP/2
> Host: content.dropboxapi.com
> User-Agent: curl/8.4.0
> Accept: */*
> Authorization: Bearer <ACCESS_TOKEN>
> Dropbox-API-Arg: {"path":"/test.txt"}
> Content-Type: application/octet-stream
>
< HTTP/2 200
< content-type: application/octet-stream
< accept-ranges: bytes
< cache-control: no-cache
< dropbox-api-result: {"name": "test.txt", "path_lower": "/test.txt", "path_display": "/test.txt", "id": "id:25N5ksooX-sAAAAAAAQYrQ", "client_modified": "2024-03-11T15:24:40Z", "server_modified": "2024-03-11T15:24:40Z", "rev": "6136423edf446021eccc7", "size": 27, "is_downloadable": true, "content_hash": "cceac37da5288a6b6716737310c14305c9b16a6e0ff0abce4a306c3de3a59f75"}
< etag: W/"6136423edf446021eccc7"
< original-content-length: 27
< x-server-response-time: 375
< date: Mon, 06 May 2024 15:09:05 GMT
< server: envoy
< strict-transport-security: max-age=31536000; includeSubDomains; preload
< x-robots-tag: noindex, nofollow, noimageindex
< content-length: 27
< x-dropbox-response-origin: far_remote
< x-dropbox-request-id: d0eb597d801d4203819d86c9b65b42a1
<
* Connection #0 to host content.dropboxapi.com left intact
This is the test file data.

curl -v -X GET https://content.dropboxapi.com/2/files/download \
    --header "Authorization: Bearer <ACCESS_TOKEN>" \
    --header "Dropbox-API-Arg: {\"path\":\"/test.txt\"}" \
    --header "Content-Type: application/octet-stream"

> GET /2/files/download HTTP/2
> Host: content.dropboxapi.com
> User-Agent: curl/8.4.0
> Accept: */*
> Authorization: Bearer <ACCESS_TOKEN>
> Dropbox-API-Arg: {"path":"/test.txt"}
> Content-Type: application/octet-stream
>
< HTTP/2 200
< content-type: application/octet-stream
< accept-ranges: bytes
< cache-control: no-cache
< content-disposition: attachment; filename=unspecified
< content-security-policy: sandbox
< dropbox-api-result: {"name": "test.txt", "path_lower": "/test.txt", "path_display": "/test.txt", "id": "id:25N5ksooX-sAAAAAAAQYrQ", "client_modified": "2024-03-11T15:24:40Z", "server_modified": "2024-03-11T15:24:40Z", "rev": "6136423edf446021eccc7", "size": 27, "is_downloadable": true, "content_hash": "cceac37da5288a6b6716737310c14305c9b16a6e0ff0abce4a306c3de3a59f75"}
< etag: W/"6136423edf446021eccc7"
< original-content-length: 27
< vary: Dropbox-API-Arg, Authorization
< x-content-security-policy: sandbox
< x-content-type-options: nosniff
< x-server-response-time: 340
< x-webkit-csp: sandbox
< date: Mon, 06 May 2024 15:09:29 GMT
< server: envoy
< strict-transport-security: max-age=31536000; includeSubDomains; preload
< x-robots-tag: noindex, nofollow, noimageindex
< content-length: 27
< x-dropbox-response-origin: far_remote
< x-dropbox-request-id: 1eaaff94c0f84f2f91cf96059913ee87
<
* Connection #0 to host content.dropboxapi.com left intact
This is the test file data.

I included the "Content-Type" request header to match your example, but it's not actually required for this. Also, I tried the GET request several times in a row without issue.

So, it does sound like this issue is environment-specific. We'd be happy to look into it further on our side to see if there's something we can do about it from the Dropbox server side, but it's unclear what the issue is exactly so far. Is there a way you could enable some more verbose output (similar to -v for curl above) to gather more information about how exactly the request is failing in the affected environments?

personalizedrefrigerator
Explorer | Level 4
7 months ago
Thank you for checking!

> I just tried it out, and confirmed that the API is still allowing both GET and POST for this endpoint in my testing

Locally, I only experience the issue when sending a GET request for the same file two or more times. The first request is successful, but subsequent requests fail, until another file is requested.

> We'd be happy to look into it further on our side to see if there's something we can do about it from the Dropbox server side, but it's unclear what the issue is exactly so far. Is there a way you could enable some more verbose output (similar to -v for curl above) to gather more information about how exactly the request is failing in the affected environments?

I'm not sure how to do this for React Native. As commented above, I was able to reproduce part of the issue in Safari/iOS. I'm attaching screenshots of the "network" tab for a failing and passing GET request in this environment.

Edit: It may be necessary to click on the image above to view it with greater resolution.
Note that I can't reproduce the POST issue in Safari.
- Greg-DB
  Dropbox Staff
  7 months ago
  Thanks! It looks like there's no response received. In cases like that, we'd need to refer to the network client error to see why that failed (e.g., DNS issue, timeout, etc.). It doesn't look like there's much there though, unfortunately. I do see the "TypeError: Load failed". Is there any additional information there if you expand those two dropdown arrows next to that? And is there anything in the "Preview" tab?
  - personalizedrefrigerator
    Explorer | Level 4
    7 months ago
    The "Preview" tab shows an error message:
    The dropdown by "TypeError: Load failed" similarly doesn't show additional information.
    
    The right-click menu for the failed request has options that might be helpful:
    
    "Copy HTTP request":
    
    GET /2/files/download Authorization: Bearer TOKEN_HERE Content-Type: application/octet-stream Origin: https://js-draw.web.app Referer: https://js-draw.web.app/ Accept: */* Sec-Fetch-Dest: empty Sec-Fetch-Mode: cors Sec-Fetch-Site: cross-site User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.2 Safari/605.1.15 Dropbox-API-Arg: {"path":"/info.json"}
    
    "Copy HTTP response":
    
    NaN null
    
    "Copy as cURL":
    
    curl 'https://content.dropboxapi.com/2/files/download' \ -X 'GET' \ -H 'Authorization: Bearer [[token]]' \ -H 'Content-Type: application/octet-stream' \ -H 'Origin: https://js-draw.web.app' \ -H 'Referer: https://js-draw.web.app/' \ -H 'Accept: */*' \ -H 'Sec-Fetch-Dest: empty' \ -H 'Sec-Fetch-Mode: cors' \ -H 'Sec-Fetch-Site: cross-site' \ -H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.2 Safari/605.1.15' \ -H 'Dropbox-API-Arg: {"path":"/info.json"}'
    
    Interestingly, the CURL request is successful when run multiple times in the MacOS terminal app.
    
    I'm now trying to see if I can log network requests made by the iOS simulator (relevant Apple documentation).