diff --git a/faerun_calendar/static/faerun_calendar/css/main.css b/faerun_calendar/static/faerun_calendar/css/main.css
index 0ff01b7..892148c 100644
--- a/faerun_calendar/static/faerun_calendar/css/main.css
+++ b/faerun_calendar/static/faerun_calendar/css/main.css
@@ -84,3 +84,12 @@ p.event-description {
     margin: 0px;
     padding: 0px;
 }
+
+p.calendar-error {
+    color: Crimson;
+    font-size: 200%;
+}
+
+p.calendar-info {
+    font-size: 200%;
+}
diff --git a/faerun_calendar/templates/faerun_calendar/index.html b/faerun_calendar/templates/faerun_calendar/index.html
index c45e636..c5b2b2a 100644
--- a/faerun_calendar/templates/faerun_calendar/index.html
+++ b/faerun_calendar/templates/faerun_calendar/index.html
@@ -18,6 +18,8 @@
     {% elif type == 'day' %}
         <h1 class="title">Календарь — События</h1>
         <h2 class="year">Год {{year_data.number}}, {{month_data.name}}, день {{day}}-й</h2>
+    {% elif type == 'error' %}
+        <h1 class="title">Календарь — Ошибка</h1>
     {% endif %}
 
     <div class="calendar">
@@ -29,7 +31,7 @@
             {% endfor %}
         {% elif type == 'day' %}
             {% if events.count == 0 %}
-                <p>Событий нет</p>
+                <p class="calendar-info">Событий нет</p>
             {% else %}
                 {% for event in events %}
                     <div class="event">
@@ -39,6 +41,14 @@
                     </div>
                 {% endfor %}
             {% endif %}
+        {% elif type == 'error' %}
+            {% if error_type == 'year' %}
+                <p class="calendar-error">Неверный год</p>
+            {% elif error_type == 'month' %}
+                <p class="calendar-error">Неверный месяц</p>
+            {% elif error_type == 'day' %}
+                <p class="calendar-error">Неверный день</p>
+            {% endif %}
         {% endif %}
     </div>
 </div>
diff --git a/faerun_calendar/views.py b/faerun_calendar/views.py
index f62471f..51cf349 100644
--- a/faerun_calendar/views.py
+++ b/faerun_calendar/views.py
@@ -9,38 +9,69 @@ from .models import Event
 
 
 def day_page(request, year: int, month: int, day: int):
-    try:
-        year_data = YearData.objects.get(number=year)
-    except YearData.DoesNotExist:
-        return HttpResponseNotFound('<h1>404 Not Found</h1>')
+    params = None
 
-    try:
-        year_id = getattr(year_data, 'id')
-    except AttributeError:
-        return HttpResponseNotFound('<h1>404 Not Found</h1>')
+    if not params:
+        try:
+            year_data = YearData.objects.get(number=year)
+        except YearData.DoesNotExist:
+            params = {'type': 'error', 'error_type': 'year'}
 
-    try:
-        month_data = MonthData.objects.get(number=month)
-    except MonthData.DoesNotExist:
-        return HttpResponseNotFound('<h1>404 Not Found</h1>')
+    if not params:
+        try:
+            year_id = getattr(year_data, 'id')
+        except AttributeError:
+            params = {'type': 'error', 'error_type': 'year'}
 
-    try:
-        month_id = getattr(month_data, 'id')
-    except AttributeError:
-        return HttpResponseNotFound('<h1>404 Not Found</h1>')
+    if not params:
+        try:
+            month_data = MonthData.objects.get(number=month)
+        except MonthData.DoesNotExist:
+            params = {'type': 'error', 'error_type': 'month'}
 
-    try:
-        events = Event.objects.filter(year=year_id, month=month_id, day=day)
-    except Event.DoesNotExist:
-        return HttpResponseNotFound(f'<h1>404 Not Found</h1>')
+    if not params:
+        try:
+            month_id = getattr(month_data, 'id')
+        except AttributeError:
+            params = {'type': 'error', 'error_type': 'month'}
 
-    params = {
-        'type': 'day',
-        'year_data': year_data,
-        'month_data': month_data,
-        'day': day,
-        'events': events,
-    }
+    if not params:
+        try:
+            events = Event.objects.filter(year=year_id, month=month_id, day=day)
+        except Event.DoesNotExist:
+            params = {'type': 'error', 'error_type': 'events'}
+
+    if not params:
+        try:
+            is_leap = getattr(year_data, 'is_leap')
+        except AttributeError:
+            params = {'type': 'error', 'error_type': 'year'}
+        else:
+            try:
+                is_leap_month = getattr(month_data, 'is_leap_month')
+            except AttributeError:
+                params = {'type': 'error', 'error_type': 'month'}
+            else:
+                if not is_leap and is_leap_month:
+                    params = {'type': 'error', 'error_type': 'month'}
+
+    if not params:
+        try:
+            is_oneday = getattr(month_data, 'is_oneday')
+        except AttributeError:
+            params = {'type': 'error', 'error_type': 'month'}
+        else:
+            if is_oneday and day != 1 or not 1 <= day <= 30:
+                params = {'type': 'error', 'error_type': 'day'}
+
+    if not params:
+        params = {
+            'type': 'day',
+            'year_data': year_data,
+            'month_data': month_data,
+            'day': day,
+            'events': events,
+        }
 
     return render(request, 'faerun_calendar/index.html', params)