diff --git a/CHANGELOG-5.11.md b/CHANGELOG-5.11.md
new file mode 100644
index 00000000000..44d94590972
--- /dev/null
+++ b/CHANGELOG-5.11.md
@@ -0,0 +1,10 @@
+# Release Notes for Craft CMS 5.11 (WIP)
+
+### Development
+- The `params` argument of the `url()` Twig function now accepts `false` to remove all params from the passed-in URL. ([#19102](https://github.com/craftcms/cms/pull/19102))
+- Added `craft\web\DbSession`, which should be used instead of `yii\web\DbSession` to prevent “headers already sent” warnings from getting logged. ([#19139](https://github.com/craftcms/cms/issues/19139))
+
+### Extensibility
+- Added `craft\helpers\UrlHelper::removeParams()`. ([#19102](https://github.com/craftcms/cms/pull/19102))
+- Added `craft\helpers\UrlHelper::removeAllParams()`. ([#19102](https://github.com/craftcms/cms/pull/19102))
+- The `$params` argument of `craft\helpers\UrlHelper::url()` now accepts `false` to remove all params from the passed-in URL. ([#19102](https://github.com/craftcms/cms/pull/19102))
diff --git a/src/helpers/UrlHelper.php b/src/helpers/UrlHelper.php
index fd4aefa9d08..e27013eb31e 100644
--- a/src/helpers/UrlHelper.php
+++ b/src/helpers/UrlHelper.php
@@ -155,12 +155,61 @@ public static function urlWithParams(string $url, array|string $params): string
      * @since 3.2.2
      */
     public static function removeParam(string $url, string $param): string
+    {
+        return static::removeParams($url, [$param]);
+    }
+
+    /**
+     * Removes query string params from a URL.
+     *
+     * @param string $url
+     * @param string[] $params
+     * @return string
+     * @since 5.11.0
+     */
+    public static function removeParams(string $url, array $params): string
+    {
+        // Extract any params/fragment from the base URL
+        [$url, $urlParams, $fragment] = self::_extractParams($url);
+
+        // Remove the params
+        foreach ($params as $param) {
+            unset($urlParams[$param]);
+        }
+
+        // Rebuild
+        if (($query = static::buildQuery($urlParams)) !== '') {
+            $url .= '?' . $query;
+        }
+        if ($fragment !== null) {
+            $url .= '#' . $fragment;
+        }
+        return $url;
+    }
+
+    /**
+     * Removes all query string params from a URL.
+     *
+     * @param string $url
+     * @param string[] $except Any params that should be left alone
+     * @return string
+     * @since 5.11.0
+     */
+    public static function removeAllParams(string $url, array $except = []): string
     {
         // Extract any params/fragment from the base URL
         [$url, $params, $fragment] = self::_extractParams($url);
 
-        // Remove the param
-        unset($params[$param]);
+        // Remove the params
+        if (!empty($except)) {
+            foreach (array_keys($params) as $param) {
+                if (!in_array($param, $except)) {
+                    unset($params[$param]);
+                }
+            }
+        } else {
+            $params = [];
+        }
 
         // Rebuild
         if (($query = static::buildQuery($params)) !== '') {
@@ -275,18 +324,20 @@ public static function rootRelativeUrl(string $url): string
      * Returns either a control panel or a site URL, depending on the request type.
      *
      * @param string $path
-     * @param array|string|null $params
+     * @param array|string|false|null $params The query params to add to the URL. If `false`, any existing params will be removed.
      * @param string|null $scheme
      * @param bool|null $showScriptName Whether the script name (index.php) should be included in the URL.
      * By default (null) it will defer to the `omitScriptNameInUrls` config setting.
      * @return string
      */
-    public static function url(string $path = '', array|string|null $params = null, ?string $scheme = null, ?bool $showScriptName = null): string
+    public static function url(string $path = '', array|string|false|null $params = null, ?string $scheme = null, ?bool $showScriptName = null): string
     {
         // Return $path if it appears to be an absolute URL.
         if (static::isFullUrl($path)) {
             if ($params) {
                 $path = static::urlWithParams($path, $params);
+            } elseif ($params === false) {
+                $path = static::removeAllParams($path);
             }
 
             if ($scheme !== null) {
@@ -312,7 +363,7 @@ public static function url(string $path = '', array|string|null $params = null,
             $scheme = 'https';
         }
 
-        return self::_createUrl($path, $params, $scheme, $cpUrl, showScriptName: $showScriptName);
+        return self::_createUrl($path, $params ?: null, $scheme, $cpUrl, showScriptName: $showScriptName);
     }
 
     /**
@@ -596,12 +647,12 @@ public static function cpReferralUrl(): ?string
         }
 
         // Make sure the CP referred it
-        if (!str_starts_with($referrer, self::baseCpUrl())) {
+        if (!str_starts_with($referrer, static::baseCpUrl())) {
             return null;
         }
 
         // to ensure we're comparing uris strip base cp url and query string from the referrer first
-        $referrerFullUri = ltrim(StringHelper::removeLeft($referrer, self::baseCpUrl()), '/');
+        $referrerFullUri = ltrim(StringHelper::removeLeft($referrer, static::baseCpUrl()), '/');
         $referrerFullUri = substr($referrerFullUri, 0, strpos($referrerFullUri, '?') ?: null);
 
         // Make sure it didn't refer itself
diff --git a/src/web/DbSession.php b/src/web/DbSession.php
new file mode 100644
index 00000000000..6963edb30f1
--- /dev/null
+++ b/src/web/DbSession.php
@@ -0,0 +1,33 @@
+<?php
+/**
+ * @link https://craftcms.com/
+ * @copyright Copyright (c) Pixel & Tonic, Inc.
+ * @license https://craftcms.github.io/license/
+ */
+
+namespace craft\web;
+
+use craft\behaviors\SessionBehavior;
+
+/**
+ * Extends [[\yii\web\DbSession]] to add defenses for “headers already sent” errors.
+ *
+ * @author Pixel & Tonic, Inc. <support@pixelandtonic.com>
+ * @since 5.11.0
+ * @mixin SessionBehavior
+ */
+class DbSession extends \yii\web\DbSession
+{
+    /**
+     * @inheritdoc
+     */
+    public function has($key): bool
+    {
+        // don't open the session if the headers were already sent
+        if (!$this->getIsActive() && headers_sent()) {
+            return isset($_SESSION[$key]);
+        }
+
+        return parent::has($key);
+    }
+}
diff --git a/tests/unit/helpers/UrlHelperTest.php b/tests/unit/helpers/UrlHelperTest.php
index 6eb9c23ce71..c30e86627a9 100644
--- a/tests/unit/helpers/UrlHelperTest.php
+++ b/tests/unit/helpers/UrlHelperTest.php
@@ -158,6 +158,39 @@ public function testStripQueryString(string $expected, string $url): void
         self::assertSame($expected, UrlHelper::stripQueryString($url));
     }
 
+    /**
+     * @dataProvider removeParamDataProvider
+     * @param string $expected
+     * @param string $url
+     * @param string $param
+     */
+    public function testRemoveParam(string $expected, string $url, string $param): void
+    {
+        self::assertSame($expected, UrlHelper::removeParam($url, $param));
+    }
+
+    /**
+     * @dataProvider removeParamsDataProvider
+     * @param string $expected
+     * @param string $url
+     * @param string[] $params
+     */
+    public function testRemoveParams(string $expected, string $url, array $params): void
+    {
+        self::assertSame($expected, UrlHelper::removeParams($url, $params));
+    }
+
+    /**
+     * @dataProvider removeAllParamsDataProvider
+     * @param string $expected
+     * @param string $url
+     * @param string[] $except
+     */
+    public function testRemoveAllParams(string $expected, string $url, array $except = []): void
+    {
+        self::assertSame($expected, UrlHelper::removeAllParams($url, $except));
+    }
+
     /**
      * @dataProvider encodeParamsDataProvider
      */
@@ -192,11 +225,11 @@ public function testRootRelativeUrl(string $expected, string $url): void
      * @dataProvider urlFunctionDataProvider
      * @param string $expected
      * @param string $path
-     * @param array|null $params
+     * @param array|string|false|null $params
      * @param string|null $scheme
      * @param bool|null $showScriptName
      */
-    public function testUrlFunction(string $expected, string $path = '', ?array $params = null, ?string $scheme = null, ?bool $showScriptName = null): void
+    public function testUrlFunction(string $expected, string $path = '', array|string|false|null $params = null, ?string $scheme = null, ?bool $showScriptName = null): void
     {
         $scheme ??= 'https';
         $expected = $this->_prepExpectedUrl($expected, $scheme);
@@ -435,6 +468,129 @@ public static function stripQueryStringDataProvider(): array
         ];
     }
 
+    /**
+     * Tests for UrlHelper::removeParam() method
+     *
+     * @return array
+     */
+    public static function removeParamDataProvider(): array
+    {
+        return [
+            'basic' => [
+                self::ABSOLUTE_URL_HTTPS . '?param2=value2',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2',
+                'param1',
+            ],
+            'last-param' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1',
+                'param1',
+            ],
+            'missing-param' => [
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1',
+                'param2',
+            ],
+            'no-params' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS,
+                'param1',
+            ],
+            'keeps-fragment' => [
+                self::ABSOLUTE_URL_HTTPS . '?param2=value2#anchor',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2#anchor',
+                'param1',
+            ],
+        ];
+    }
+
+    /**
+     * Tests for UrlHelper::removeParams() method
+     *
+     * @return array
+     */
+    public static function removeParamsDataProvider(): array
+    {
+        return [
+            'multiple' => [
+                self::ABSOLUTE_URL_HTTPS . '?param2=value2',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2&param3=value3',
+                ['param1', 'param3'],
+            ],
+            'all-params' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2',
+                ['param1', 'param2'],
+            ],
+            'missing-params' => [
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1',
+                ['param2', 'param3'],
+            ],
+            'empty-params' => [
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1',
+                [],
+            ],
+            'no-params' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS,
+                ['param1'],
+            ],
+            'keeps-fragment' => [
+                self::ABSOLUTE_URL_HTTPS . '?param2=value2#anchor',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2&param3=value3#anchor',
+                ['param1', 'param3'],
+            ],
+        ];
+    }
+
+    /**
+     * Tests for UrlHelper::removeAllParams() method
+     *
+     * @return array
+     */
+    public static function removeAllParamsDataProvider(): array
+    {
+        return [
+            'basic' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2',
+                [],
+            ],
+            'except' => [
+                self::ABSOLUTE_URL_HTTPS . '?param2=value2',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2&param3=value3',
+                ['param2'],
+            ],
+            'except-multiple' => [
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param3=value3',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2&param3=value3',
+                ['param1', 'param3'],
+            ],
+            'except-missing' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2',
+                ['param3'],
+            ],
+            'no-params' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS,
+                [],
+            ],
+            'keeps-fragment' => [
+                self::ABSOLUTE_URL_HTTPS . '#anchor',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2#anchor',
+                [],
+            ],
+            'except-keeps-fragment' => [
+                self::ABSOLUTE_URL_HTTPS . '?param2=value2#anchor',
+                self::ABSOLUTE_URL_HTTPS . '?param1=value1&param2=value2#anchor',
+                ['param2'],
+            ],
+        ];
+    }
+
     /**
      * Tests for UrlHelper::urlWithParams() method
      *
@@ -716,6 +872,11 @@ public static function urlFunctionDataProvider(): array
                 ['returnUrl' => 'https://example.test/admin/entries?site={handle}'],
                 'https',
             ],
+            'remove-params' => [
+                self::ABSOLUTE_URL_HTTPS,
+                self::ABSOLUTE_URL_HTTPS . '?x-craft-preview=foo&test=bar',
+                false,
+            ],
         ];
     }