Without seeing a log files I can only guess:
The "server 2" knows a root certificate used to sign your FTPS server's certificate (it's in Windows certificate store). So it does not need/use the TlsHostCertificateFingerprint.
The "server 1" does not know the root certificate.

martin wrote:

What is the question?

1) Why it works on one machine even with a wrong fingerprint?
2) Or that "fingerprint not working" - Though then I do not understand what is not working.

This is the problem. I can't understand why on one it works ...
checking the server logs, it seems that I don't check the fingerprint and accepts any certificate as if I had enabled

while I set it to false.

I give a more specific example:
server 1 fingerprint -> XX: XY: ZZ -> OK
server 1 fingerprint -> XX: XX: XX -> ERROR

server 2 fingerprint -> XX: XX: XX OK
server 2 fingerprint -> XX: XY: ZZ OK
server 2 fingerprint -> 11:11:11 OK

moreover the two servers have the same configuration.

I also tried to change computers and ip to connect but nothing

What is the question?

1) Why it works on one machine even with a wrong fingerprint?
2) Or that "fingerprint not working" - Though then I do not understand what is not working.

Hi,
i'm using WinSCP 5.15 and i can't understand why fingerprint checking doesn't work, I'll explain the problem:

The problem is that in the local server (192.168.x.x) it only connects if the fingerprint is correct, while in another server (not local) it connects even if the fingerprint is not correct (obviously in the right format).

as fingerprint format i use: "XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX:XX"

this is my code:

[code]
With sessionOptions
.Protocol = Protocol.Ftp
.HostName = ftpAddress
.UserName = ftpUser
.Password = ftpPassword
.PortNumber = 21
.TimeoutInMilliseconds = timeoutFtp
End With

If enableFtps.Checked = True Then
sessionOptions.FtpSecure = FtpSecure.Explicit
If trustCertificate.Checked = True Then
sessionOptions.TlsHostCertificateFingerprint = sslHostFingerprint
sessionOptions.GiveUpSecurityAndAcceptAnyTlsHostCertificate = False
Else
sessionOptions.GiveUpSecurityAndAcceptAnyTlsHostCertificate = True
End If
End If
[/code]

thanks in advance