FileZilla Forums

I am getting a lot of the following errors when user try to upload a file
450 TLS session of data connection has not resumed or the session does not match the control connection

This is not happening for all users

One of the users reported this exception from their software:
javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake
java.io.EOFException: SSL peer shut down incorrectly

It's a security feature preventing data connection stealing attacks. Make sure your client reuses the session of the control connection on the data connection. Not only is this needed for security, it incidentally is also a lot faster.