Copy Data from FTP error

Decock Reinout 0

Since yesterday, copying data from an FTP server with Azure Data Factory sometimes works, sometimes errors.

Any idea where to look?

Connection test is succesfull.
Number of retries is set to 3
We switch from parallel processing to sequential processing
We limited the number of connections to 1
We enabled/disabled server certificate validation

Nothing seems to work.

Here's an example of an error:

ErrorCode=FtpFailedToReadFtpData,'Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException,Message=Failed to read FTP data. Message: 'Failed to read data from ftp: The remote server returned an error: (425) Can't open data connection.',Source=Microsoft.DataTransfer.ClientLibrary,''Type=System.Net.WebException,Message=The remote server returned an error: (425) Can't open data connection.,Source=System,'

Decock Reinout 0 Reputation points

2023-12-14T16:01:44.1533333+00:00
phemanth 6,635 Reputation points Microsoft Vendor

2023-12-15T09:27:38.5166667+00:00
@Decock Reinout

Thanks for recahing out MS Q&A

The error code 425 in FTP is typically related to data connection issues. This can be due to a variety of reasons, including firewall settings or issues with passive mode123. Here are a few suggestions:

Check the Firewall Settings: Ensure that the port range between 1024 to 65535 is open for data transfer under passive mode supported by the data factory or Synapse pipeline.

Active/Passive Mode Settings: The most common reason that this error occurs is a mis-configuration of the FTP server software itself, related to SSL connections and firewalls, in which the connection tries to establish itself on a bad IP address3. You might need to switch between active and passive modes depending on your server configuration.

FTP has a control connection and a data connection. The control connection is started from the client to the server and thus makes usually no problems, but the data connections are different:

in active mode the server tries to connect to the client. The necessary IP and port setting are send within the PORT or EPRT command inide the control channel. If the client is behind active mode will not work, because the client uses an IP address not reachable by the server. Similar problems are if the client is behind a firewall, because connections from outside will simply be blocked. Only FTP aware firewalls might employ special helpers to manage active connections (and these will not work with FTPS).

in passive mode the client connects to the server. The necessary IP and port are send within the response to the PASV or EPSV commands. There are no problems with NAT on the client side and usually no problems with firewalls either. But there will be problems if the server itself is behind firewall or NAT.

Server Configuration: If you’re using a Linux server, you might want to try the command setsebool -P ftpd_connect_all_unreserved

Hope this helps. Do let us know if you any further queries.
phemanth 6,635 Reputation points Microsoft Vendor

2023-12-18T11:20:05.9433333+00:00

@Decock Reinout We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
phemanth 6,635 Reputation points Microsoft Vendor

2023-12-19T04:13:39.1766667+00:00

@Decock Reinout just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.

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Copy Data from FTP error