Kennisbank

Problem

When connecting to FileZilla Server 1.x the following error is logged:
425 Unable to build data connection: TLS session of data connection not resumed.

Cause

This issue is caused by a bug in GnuTLS:
FileZilla Forum - TLS session of data connection not resumed Error (v1.1.0)
GnuTLS ticket

Workaround

Temporary disable TLS 1.3 for Schannel:

1. Import (double click) "Disable TLS 1.3.reg" from Disable TLS 1.3.zip
2. Restart SmartFTP

Manual steps:

1. Open regedit.exe
2. Create this key if it doesn't exist yet:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.3\Client
3. Create a new DWORD (32) Value:
   Enabled
   Set the value to 0x0
4. Restart SmartFTP