Fix an error where 'false' string is displayed when we add a new parameter in the Parameters tab,

also clear the old value when the user changes the parameter name.

Corrected the implementation of BooleanCellFormatter.

Fixes #4753

docs/en_US/release_notes_4_14.rst

@@ -23,6 +23,7 @@ Bug fixes
 | `Issue #4199 <https://redmine.postgresql.org/issues/4199>`_ -  Ensure that 'ENTER' key in the data filter should not run the query.
 | `Issue #4728 <https://redmine.postgresql.org/issues/4728>`_ -  Highlighted the color of closing or opening parenthesis when user select them in CodeMirror.
 | `Issue #4751 <https://redmine.postgresql.org/issues/4751>`_ -  Fix issue where export job fails when deselecting all the columns.
+| `Issue #4753 <https://redmine.postgresql.org/issues/4753>`_ -  Fix an error where 'false' string is displayed when we add a new parameter in the Parameters tab, also clear the old value when the user changes the parameter name.
 | `Issue #4755 <https://redmine.postgresql.org/issues/4755>`_ -  Ensure that pgAdmin should work behind reverse proxy if the inbuilt server is used as it is.
 | `Issue #4756 <https://redmine.postgresql.org/issues/4756>`_ -  Fix issue where pgAdmin does not load completely if loaded in an iframe.
 | `Issue #4760 <https://redmine.postgresql.org/issues/4760>`_ -  Ensure the search path should not be quoted for Database.

web/pgadmin/browser/server_groups/servers/static/js/variable.js

@@ -87,7 +87,8 @@ function(gettext, _, $, Backbone, Backform, Backgrid, Alertify, pgAdmin, pgNode)
         setTimeout(function() {
           self.columns.each(function(col) {
             if (col.get('name') == 'value') {
-
+              // Reset old value
+              self.model.set({'value': undefined}, {silent:true});
               var idx = self.columns.indexOf(col),
                 cf = col.get('cellFunction'),
                 cell = new (cf.apply(col, [self.model]))({

web/pgadmin/static/js/backgrid.pgadmin.js

@@ -1890,7 +1890,8 @@ define([
     },
   });
 
-  Backgrid.BooleanCellFormatter = _.extend(Backgrid.CellFormatter.prototype, {
+  var BooleanCellFormatter = Backgrid.BooleanCellFormatter = function() {};
+  _.extend(BooleanCellFormatter.prototype, {
     fromRaw: function (rawValue) {
       if (_.isUndefined(rawValue) || _.isNull(rawValue)) {
         return false;