When an FTP File Transfer with ftp_put Fails in PHP, Is It Caused by FTP Mode Improperly Set?

Troubleshooting ftp_put Failure in PHP

Problem:

When attempting to upload an XML file to an FTP server using the ftp_put function in PHP, the operation fails, returning false.

Cause:

One common cause of ftp_put failures is that PHP defaults to using the active FTP mode, which is often incompatible with many FTP servers due to firewall or network restrictions. Switching to the passive mode usually resolves this issue.

Solution:

To switch to the passive mode in PHP, use the ftp_pasv function after establishing an FTP connection:

<code class="php">$connect = ftp_connect($ftp) or die("Unable to connect to host");
ftp_login($connect, $username, $pwd) or die("Authorization failed");

// Turn passive mode on
ftp_pasv($connect, true) or die("Unable to switch to passive mode");</code>

Additional Considerations:

• Ensure that the ftp_login function is called before invoking ftp_pasv. Otherwise, it will not have any effect.
• If the FTP server reports an incorrect IP address in response to the PASV command, consider using the following option:

<code class="php">ftp_set_option($connect, FTP_USEPASVADDRESS, false);</code>

• Note that switching to passive mode may not be sufficient if the FTP server's configuration or firewall settings are causing issues. In such cases, consult with the server administrator to determine the root cause and implement the necessary fixes.

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