FTP Failures on Large Files

Question

I am using the free edition of edtFTP to transfer files. It seems to work fabulously with files under 200MB, but when I try to do large files, I get errors. The larger the file, the more errors I get. I am talking about files from 200MB to 1.5GB or larger. It SEEMS like it gets 100% of the file transferred, THEN errors. (The code is running in the cloud, and is hard to debug cause of that.). I am seeing mostly this error:


I see this error after the file seems to be fully or close to full uploaded:

EnterpriseDT.Net.Ftp.ControlChannelIOException: Unable to read data from the transport connection: 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.

I've tried 2 different FTP servers (2 different major CDNs), and see the same issue with both, so I don't think it is the FTP server. And my application is running on a MAJOR cloud provider, so I am dubious it is a networking problem.

ANY advice is greatly appreciated!
Mark :cry:

Answer 1

This often occurs for larger files when the FTP server times out the connection while transferring. You will see this behaviour with any FTP client if you transfer a file that is big enough.

The only ways around this is to increase the timeout in the server, or to transfer the file in parts, appending to what has already been transferred.