If you get this error when you try to use a FTP connection with SSL please try to first connect to the FTP site with a Filezilla.
If you are prompted to accept a certificate in Filezilla before establishing the connection, you may be trying to connect to a FTP site that is using a certificate that is not signed by a trusted Root Certificate Authority.
Please contact the FTP provider and get a copy of the certificate that needs to be used to establish the FTP connection. You need to import that certificate into the Java Keystore that the atom is set to use (see How to Add Certificate to the Java Keystore). Note that you can only import the certificate in to the Java keystore that is used on a local atom. Dell Boomi will not allow the importing of private certificates in the Dell Boomi Atom Cloud.
You will also need to verify that the atom is using the JCE Unlimited Strength Jurisdiction Policy Files. You can verify this in Atom Management; Atom Startup Properties tab. If the value for the Unlimited Strength Cryptography property is false you will need to Install JCE Unlimited Strength Jurisdiction policy files.
A successful install of the Unlimited Strength Cryptography property will change that property from false to true.