diff --git a/koha-tmpl/intranet-tmpl/prog/en/includes/calendar.inc b/koha-tmpl/intranet-tmpl/prog/en/includes/calendar.inc
index 07125a6faa..84be618d60 100644
--- a/koha-tmpl/intranet-tmpl/prog/en/includes/calendar.inc
+++ b/koha-tmpl/intranet-tmpl/prog/en/includes/calendar.inc
@@ -155,7 +155,6 @@
                 }
             },
             onClose: function( selectedDates, dateText, instance) {
-                validate_date( dateText, instance );
                 var thisInput = instance.input;
                 if ( thisInput.hasAttribute('data-date_to') ) {
                     var endPickerEl = document.querySelector("#"+thisInput.dataset.date_to);
diff --git a/koha-tmpl/intranet-tmpl/prog/js/calendar.js b/koha-tmpl/intranet-tmpl/prog/js/calendar.js
index e1637b2ba7..7d35b680d4 100644
--- a/koha-tmpl/intranet-tmpl/prog/js/calendar.js
+++ b/koha-tmpl/intranet-tmpl/prog/js/calendar.js
@@ -9,53 +9,6 @@ if (debug > 1) {
     );
 }
 
-function is_valid_date(date) {
-    // An empty string is considered as a valid date for convenient reasons.
-    if (date === "") return 1;
-    var dateformat = flatpickr_dateformat_string;
-    if (dateformat == "us") {
-        if (date.search(/^\d{2}\/\d{2}\/\d{4}($|\s)/) == -1) return 0;
-        dateformat = "m/d/Y";
-    } else if (dateformat == "metric") {
-        if (date.search(/^\d{2}\/\d{2}\/\d{4}($|\s)/) == -1) return 0;
-        dateformat = "d/m/Y";
-    } else if (dateformat == "iso") {
-        if (date.search(/^\d{4}-\d{2}-\d{2}($|\s)/) == -1) return 0;
-        dateformat = "Y-m-d";
-    } else if (dateformat == "dmydot") {
-        if (date.search(/^\d{2}\.\d{2}\.\d{4}($|\s)/) == -1) return 0;
-        dateformat = "d.m.Y";
-    }
-    try {
-        flatpickr.parseDate(date, dateformat);
-    } catch (e) {
-        return 0;
-    }
-    return 1;
-}
-
-function get_dateformat_str(dateformat) {
-    var dateformat_str;
-    if (dateformat == "us") {
-        dateformat_str = "mm/dd/yyyy";
-    } else if (dateformat == "metric") {
-        dateformat_str = "dd/mm/yyyy";
-    } else if (dateformat == "iso") {
-        dateformat_str = "yyyy-mm-dd";
-    } else if (dateformat == "dmydot") {
-        dateformat_str = "dd.mm.yyyy";
-    }
-    return dateformat_str;
-}
-
-function validate_date(dateText, inst) {
-    if (!is_valid_date(dateText)) {
-        var dateformat_str = get_dateformat_str(dateformat_pref);
-        alert(MSG_PLEASE_ENTER_A_VALID_DATE.format(dateformat_str));
-        inst.clear();
-    }
-}
-
 function Date_from_syspref(dstring) {
     var dateX = dstring.split(/[-/.]/);
     if (debug > 1 && sentmsg < 1) {
diff --git a/koha-tmpl/intranet-tmpl/prog/js/onboarding.js b/koha-tmpl/intranet-tmpl/prog/js/onboarding.js
index d0fd499060..3bb1754894 100644
--- a/koha-tmpl/intranet-tmpl/prog/js/onboarding.js
+++ b/koha-tmpl/intranet-tmpl/prog/js/onboarding.js
@@ -130,7 +130,6 @@ $(document).ready(function () {
                     return $("#enrolmentperiod").val() === "";
                 },
                 enrollment_period: true,
-                // is_valid_date ($(#"enrolementperioddate").val());
             },
             dateofbirthrequired: {
                 digits: true,
diff --git a/koha-tmpl/opac-tmpl/bootstrap/en/includes/calendar.inc b/koha-tmpl/opac-tmpl/bootstrap/en/includes/calendar.inc
index 6b9fbe3289..c177e05683 100644
--- a/koha-tmpl/opac-tmpl/bootstrap/en/includes/calendar.inc
+++ b/koha-tmpl/opac-tmpl/bootstrap/en/includes/calendar.inc
@@ -42,20 +42,6 @@
             altinput_dateformat = 'yyyy/mm/dd';
             delimiter = "-";
     }
-
-    function get_dateformat_str(dateformat) {
-        var dateformat_str;
-        if (dateformat == 'us') {
-            dateformat_str = 'mm/dd/yyyy';
-        } else if (dateformat == 'metric') {
-            dateformat_str = 'dd/mm/yyyy';
-        } else if (dateformat == 'iso') {
-            dateformat_str = 'yyyy-mm-dd';
-        } else if (dateformat == 'dmydot') {
-            dateformat_str = 'dd.mm.yyyy';
-        }
-        return dateformat_str;
-    }
 </script>
 [% Asset.js("lib/flatpickr/flatpickr.min.js") | $raw %]
 [% Asset.js("lib/maskito/maskito.core.js") | $raw %]
@@ -117,7 +103,6 @@
             new Maskito(instance.altInput, options);
         },
         onClose: function (selectedDates, dateText, instance) {
-            validate_date(dateText, instance);
             var thisInput = instance.input;
             if (thisInput.hasAttribute("data-start_for")) {
                 var endPicker = document.querySelector("#" + thisInput.dataset.start_for)._flatpickr;
@@ -128,39 +113,6 @@
 
     var MSG_PLEASE_ENTER_A_VALID_DATE = _("Please enter a valid date (should match %s).");
 
-    function is_valid_date(date) {
-        // An empty string is considered as a valid date for convenient reasons.
-        if (date === "") return 1;
-        var dateformat = flatpickr_dateformat_string;
-        switch (dateformat_pref) {
-            case "us":
-                flatpickr_dateformat_string = "m/d/Y";
-                break;
-            case "metric":
-                flatpickr_dateformat_string = "d/m/Y";
-                break;
-            case "dmydot":
-                flatpickr_dateformat_string = "d.m.Y";
-                break;
-            default:
-                flatpickr_dateformat_string = "Y-m-d";
-        }
-        try {
-            flatpickr.parseDate(date, dateformat);
-        } catch (e) {
-            return 0;
-        }
-        return 1;
-    }
-
-    function validate_date(dateText, inst) {
-        if (!is_valid_date(dateText)) {
-            var dateformat_str = get_dateformat_str(dateformat_pref);
-            alert(MSG_PLEASE_ENTER_A_VALID_DATE.format(dateformat_str));
-            inst.clear();
-        }
-    }
-
     $(document).ready(function () {
         $(".flatpickr").each(function () {
             let options = {};