'Validation' should be set to '(none)' in links with 'Method' set to 'Navigate'
You have a Link widget with the Method property set to 'Navigate' and the Validation property set to either 'Client & Server' or 'Server'. To validate the end-user typed values, you have to submit them.
Edit your Link and set the Validation property to '(none)' or change the Method property to 'Submit'.
'<destination_screen>' should be either a Frequent Destination or the target of a connector from '<originator_screen>'.
You have a Link/Button widget on screen <originator_screen> that are navigating to a <destination_screen> (in the Destination property). No connector exists from <originator_screen> to <destination_screen> and neither the <destination_screen> has its Is Freq.Destination property set to 'Yes'.
Edit your web flow and connect the two screens or set the Is Freq.Destination property of the <destination_screen> screen to Yes. If you were explicitly trying to disconnect the two screens, you must edit the Destination property in the <originator_screen> widget and select from the drop down list either '(none)' or a different destination.