Fixing TightVNC file association in windows is not as straightforward as choosing "always use TightVNC Viewer to open .vnc files"

Using this method to restore TightVNC file association results in the following error when attempting to open VNC files: Connection parameters [host, port, socket, gates] is empty
.

To fix this error, we must update the system registry. Navigate to HKEY_CURRENT_USER\SOFTWARE\Classes\Applications\tvnviewer.exe\shell\open\command
and add -optionsfile=
to the default value before the %1
(as shown).

To see other command line options, do:
c:
cd "Program Files\TightVNC"
tvnviewer.exe -help
The other options are as follows:
The following OPTIONS are supported (all of them should be used in the
form -option=VALUE where both option name and value are case-insensitive):
-optionsfile The specified file will be read and the corresponding
connection will be restored (use Save Connection Info
to create such files).
-host Connect to the specified host name.
-port Specify the port number.
-password Specify the password for authenticating to the server.
-logpath Specify the path to logfile.