diff --git a/admin/src/Fields/Validator.php b/admin/src/Fields/Validator.php
index 7ed84853..6e9c407a 100644
--- a/admin/src/Fields/Validator.php
+++ b/admin/src/Fields/Validator.php
@@ -2,10 +2,11 @@
 
 namespace Formwork\Admin\Fields;
 
-use Formwork\Core\Formwork;
 use Formwork\Data\Collection;
 use Formwork\Data\DataGetter;
-use DateTime;
+use Formwork\Utils\Date;
+use Formwork\Utils\Str;
+use InvalidArgumentException;
 
 class Validator
 {
@@ -112,14 +113,11 @@ class Validator
             return null;
         }
 
-        $format = Formwork::instance()->option('date.format');
-        $date = date_create_from_format($format, $value) ?: date_create($value);
-
-        if ($date instanceof DateTime) {
-            return date_format($date, 'Y-m-d');
+        try {
+            return date('Y-m-d', Date::toTimestamp($value, null, true));
+        } catch (InvalidArgumentException $e) {
+            throw new ValidationException('Invalid value for field "' . $field->name() . '" of type "' . $field->type() . '":' . Str::after($e->getMessage(), ':'));
         }
-
-        throw new ValidationException('Invalid date format for field "' . $field->name() . '" of type "' . $field->type() . '"');
     }
 
     /**
diff --git a/admin/src/Statistics.php b/admin/src/Statistics.php
index 96033a01..738dc896 100644
--- a/admin/src/Statistics.php
+++ b/admin/src/Statistics.php
@@ -4,6 +4,7 @@ namespace Formwork\Admin;
 
 use Formwork\Admin\Utils\IPAnonymizer;
 use Formwork\Admin\Utils\Registry;
+use Formwork\Utils\Date;
 use Formwork\Utils\FileSystem;
 use Formwork\Utils\HTTPRequest;
 use Formwork\Utils\Visitor;
@@ -151,7 +152,7 @@ class Statistics
         $uniqueVisits = array_slice($uniqueVisits, -$limit, null, true);
 
         $label = static function (string $day): string {
-            $time = strtotime($day);
+            $time = Date::toTimestamp($day, self::DATE_FORMAT);
             $month = Admin::instance()->label('date.months.short')[date('n', $time) - 1];
             $weekday = Admin::instance()->label('date.weekdays.short')[date('N', $time) % 7];
             $day = date('j', $time);
diff --git a/admin/src/Updater.php b/admin/src/Updater.php
index f99f53c4..ba0c9ed4 100644
--- a/admin/src/Updater.php
+++ b/admin/src/Updater.php
@@ -5,6 +5,7 @@ namespace Formwork\Admin;
 use Formwork\Admin\Utils\Registry;
 use Formwork\Core\Formwork;
 use Formwork\Parsers\JSON;
+use Formwork\Utils\Date;
 use Formwork\Utils\FileSystem;
 use Formwork\Utils\Str;
 use RuntimeException;
@@ -253,7 +254,7 @@ class Updater
         $this->release = [
             'name'    => $data['name'],
             'tag'     => $data['tag_name'],
-            'date'    => strtotime($data['published_at']),
+            'date'    => Date::toTimestamp($data['published_at'], DATE_ISO8601),
             'archive' => $data['zipball_url']
         ];
 
diff --git a/formwork/Core/Formwork.php b/formwork/Core/Formwork.php
index 495c9f14..8c421421 100644
--- a/formwork/Core/Formwork.php
+++ b/formwork/Core/Formwork.php
@@ -10,6 +10,7 @@ use Formwork\Parsers\YAML;
 use Formwork\Router\RouteParams;
 use Formwork\Router\Router;
 use Formwork\Traits\SingletonTrait;
+use Formwork\Utils\Date;
 use Formwork\Utils\FileSystem;
 use Formwork\Utils\Header;
 use Formwork\Utils\HTTPRequest;
@@ -336,8 +337,8 @@ final class Formwork
                     return $this->site->errorPage();
                 }
                 if ($this->option('cache.enabled') && ($page->has('publish-date') || $page->has('unpublish-date'))) {
-                    if (($page->published() && !$this->site->modifiedSince((int) strtotime($page->get('publish-date'))))
-                    || (!$page->published() && !$this->site->modifiedSince((int) strtotime($page->get('unpublish-date'))))) {
+                    if (($page->published() && !$this->site->modifiedSince(Date::toTimestamp($page->get('publish-date'))))
+                    || (!$page->published() && !$this->site->modifiedSince(Date::toTimestamp($page->get('unpublish-date'))))) {
                         // Clear cache if the site was not modified since the page has been published or unpublished
                         $this->cache->clear();
                         FileSystem::touch($this->option('content.path'));
diff --git a/formwork/Core/Page.php b/formwork/Core/Page.php
index 463b7f8e..beb6311f 100644
--- a/formwork/Core/Page.php
+++ b/formwork/Core/Page.php
@@ -7,6 +7,7 @@ use Formwork\Metadata\Metadata;
 use Formwork\Parsers\Markdown;
 use Formwork\Parsers\YAML;
 use Formwork\Template\Template;
+use Formwork\Utils\Date;
 use Formwork\Utils\FileSystem;
 use Formwork\Utils\Header;
 use Formwork\Utils\Str;
@@ -288,7 +289,7 @@ class Page extends AbstractPage
             $format = Formwork::instance()->option('date.format');
         }
         if ($this->has('publish-date')) {
-            return date($format, strtotime($this->data['publish-date']));
+            return date($format, Date::toTimestamp($this->data['publish-date']));
         }
         return parent::date($format);
     }
@@ -572,11 +573,11 @@ class Page extends AbstractPage
         $this->published = $this->data['published'];
 
         if ($this->has('publish-date')) {
-            $this->published = $this->published && strtotime($this->get('publish-date')) < time();
+            $this->published = $this->published && Date::toTimestamp($this->get('publish-date')) < time();
         }
 
         if ($this->has('unpublish-date')) {
-            $this->published = $this->published && strtotime($this->get('unpublish-date')) > time();
+            $this->published = $this->published && Date::toTimestamp($this->get('unpublish-date')) > time();
         }
 
         $this->routable = $this->data['routable'];
diff --git a/formwork/Utils/Date.php b/formwork/Utils/Date.php
new file mode 100644
index 00000000..519ba557
--- /dev/null
+++ b/formwork/Utils/Date.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace Formwork\Utils;
+
+use Formwork\Core\Formwork;
+use DateTime;
+use Exception;
+use InvalidArgumentException;
+
+class Date
+{
+    /**
+     * Parse a date according to a given format (or the default format if not given) and return the timestamp
+     *
+     * @param $throwOnError Whether to throw an Exception when the method fails or trigger a deprecation error (@internal)
+     */
+    public static function toTimestamp(string $date, string $format = null, bool $throwOnError = false): int
+    {
+        $isFormatGiven = $format !== null;
+
+        if (!$isFormatGiven) {
+            $format = Formwork::instance()->option('date.format');
+        }
+
+        $dateTime = DateTime::createFromFormat($format, $date);
+
+        if ($dateTime === false) {
+            if ($isFormatGiven) {
+                throw new InvalidArgumentException('Date "' . $date . '" is not formatted according to the format "' . $format . '": ' . static::getLastDateTimeError());
+            }
+            try {
+                $dateTime = new DateTime($date);
+            } catch (Exception $e) {
+                $message = 'Invalid date "' . $date . '": ' . static::getLastDateTimeError();
+                // TODO: this will always be the case in 2.0
+                if ($throwOnError) {
+                    throw new InvalidArgumentException($message, $e->getCode(), $e->getPrevious());
+                }
+                trigger_error('Using invalid dates is deprecated since Formwork 1.11.0. ' . $message, E_USER_DEPRECATED);
+            }
+        }
+
+        return $dateTime instanceof DateTime ? $dateTime->getTimestamp() : strtotime($date);
+    }
+
+    /**
+     * Return a human-readable string containing details about last DateTime error
+     */
+    protected static function getLastDateTimeError(): string
+    {
+        $result = [];
+        $lastError = null;
+        if (($errors = DateTime::getLastErrors()) !== false) {
+            foreach ($errors['errors'] as $position => $error) {
+                $currentError = lcfirst(rtrim($error, '.'));
+                $result[] = ($currentError !== $lastError ? $currentError . ' at position ' : '') . $position;
+                $lastError = $currentError;
+            }
+        }
+        return implode(', ', $result);
+    }
+}