If your VNC desktop has credential stuffing enabled (i.e. it has an entry in one of the username or password fields in its expanded configuration under Resources/Desktops), the connector and VNC server must mutually support a protocol which allows for credential exchange. If the connector cannot negotiate a protocol compatible with credential stuffing, it will fail with this message. The following screenshot provides an example. Note the red bar.

The connector supports the following protocols which allow for credential stuffing:

• VNC Authentication (Type 2)
• RA2 (Type 5)
• RA2r (Type 13)
• RA2_256 (Type 129)

To overcome this problem, either disable credential stuffing, or configure the server so that it supports one of the above protocols.