diff --git a/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URL.java b/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URL.java
index 285febb9813..e89250bf16c 100644
--- a/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URL.java
+++ b/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URL.java
@@ -21,8 +21,11 @@
 import static com.gargoylesoftware.htmlunit.javascript.configuration.SupportedBrowser.FF78;
 
 import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.util.stream.Collectors;
 
 import org.apache.commons.lang3.StringUtils;
+import org.apache.http.client.utils.URIBuilder;
 
 import com.gargoylesoftware.htmlunit.javascript.SimpleScriptable;
 import com.gargoylesoftware.htmlunit.javascript.configuration.JsxClass;
@@ -48,7 +51,7 @@
 @JsxClass
 public class URL extends SimpleScriptable {
 
-    private java.net.URL url_;
+    private URIBuilder url_;
 
     /**
      * Creates an instance.
@@ -73,15 +76,16 @@ public URL(final String url, final Object base) {
 
         try {
             if (StringUtils.isBlank(baseStr)) {
-                url_ = UrlUtils.toUrlUnsafe(url);
+                url_ = new URIBuilder(url);
             }
             else {
                 final java.net.URL baseUrl = UrlUtils.toUrlUnsafe(baseStr);
-                url_ = new java.net.URL(baseUrl, url);
+                url_ = new URIBuilder(new java.net.URL(baseUrl, url).toURI());
             }
             checkRemoveRedundantPort();
+            url_.build().toURL(); //validate
         }
-        catch (final MalformedURLException e) {
+        catch (final URISyntaxException | MalformedURLException e) {
             throw ScriptRuntime.typeError(e.toString());
         }
     }
@@ -121,7 +125,7 @@ public String getHash() {
         if (url_ == null) {
             return null;
         }
-        final String ref = url_.getRef();
+        final String ref = url_.getFragment();
         return ref == null ? "" : "#" + ref;
     }
 
@@ -130,7 +134,7 @@ public void setHash(final String fragment) throws MalformedURLException {
         if (url_ == null) {
             return;
         }
-        url_ = UrlUtils.getUrlWithNewRef(url_, StringUtils.isEmpty(fragment) ? null : fragment);
+        url_.setFragment(StringUtils.isEmpty(fragment) ? null : fragment);
     }
 
     /**
@@ -179,29 +183,26 @@ public void setHost(final String host) throws MalformedURLException {
             // back to string
         }
 
-        url_ = UrlUtils.getUrlWithNewHost(url_, newHost);
+        url_.setHost(newHost);
 
         final String newPort = StringUtils.substringAfter(host, ':');
         if (StringUtils.isNotBlank(newHost)) {
             try {
-                url_ = UrlUtils.getUrlWithNewHostAndPort(url_, newHost, Integer.parseInt(newPort));
+                url_.setPort(Integer.parseInt(newPort));
             }
             catch (final Exception e) {
                 // back to string
             }
         }
-        else {
-            url_ = UrlUtils.getUrlWithNewHost(url_, newHost);
-        }
 
         checkRemoveRedundantPort();
     }
 
     /** Removes port if it can be deduced from protocol */
-    private void checkRemoveRedundantPort() throws MalformedURLException {
-        if (("https".equals(url_.getProtocol()) && url_.getPort() == 443)
-                || ("http".equals(url_.getProtocol()) && url_.getPort() == 80)) {
-            url_ = UrlUtils.getUrlWithNewPort(url_, -1);
+    private void checkRemoveRedundantPort() {
+        if (("https".equals(url_.getScheme()) && url_.getPort() == 443)
+                || ("http".equals(url_.getScheme()) && url_.getPort() == 80)) {
+            url_.setPort(-1);
         }
     }
 
@@ -222,11 +223,11 @@ public String getHostname() {
     public void setHostname(final String hostname) throws MalformedURLException {
         if (getBrowserVersion().hasFeature(JS_ANCHOR_HOSTNAME_IGNORE_BLANK)) {
             if (!StringUtils.isBlank(hostname)) {
-                url_ = UrlUtils.getUrlWithNewHost(url_, hostname);
+                url_.setHost(hostname);
             }
         }
         else if (!StringUtils.isEmpty(hostname)) {
-            url_ = UrlUtils.getUrlWithNewHost(url_, hostname);
+            url_.setHost(hostname);
         }
     }
 
@@ -243,12 +244,12 @@ public String getHref() {
     }
 
     @JsxSetter
-    public void setHref(final String href) throws MalformedURLException {
+    public void setHref(final String href) throws URISyntaxException {
         if (url_ == null) {
             return;
         }
 
-        url_ = UrlUtils.toUrlUnsafe(href);
+        url_ = new URIBuilder(href);
         checkRemoveRedundantPort();
     }
 
@@ -261,7 +262,7 @@ public Object getOrigin() {
             return null;
         }
 
-        return url_.getProtocol() + "://" + url_.getHost();
+        return url_.getScheme() + "://" + url_.getHost();
     }
 
     /**
@@ -273,7 +274,7 @@ public URLSearchParams getSearchParams() {
             return null;
         }
 
-        final URLSearchParams searchParams = new URLSearchParams(url_.getQuery());
+        final URLSearchParams searchParams = new URLSearchParams(url_);
         searchParams.setParentScope(getParentScope());
         searchParams.setPrototype(getPrototype(searchParams.getClass()));
         return searchParams;
@@ -298,8 +299,9 @@ public void setPassword(final String password) throws MalformedURLException {
         if (url_ == null) {
             return;
         }
-
-        url_ = UrlUtils.getUrlWithNewUserPassword(url_, password.isEmpty() ? null : password);
+        url_.setUserInfo(UrlUtils.getUserInfoWithNewUserPassword(
+                url_.getUserInfo(),
+                password.isEmpty() ? null : password));
     }
 
     /**
@@ -312,7 +314,7 @@ public String getPathname() {
         }
 
         final String path = url_.getPath();
-        return path.isEmpty() ? "/" : path;
+        return StringUtils.isBlank(path) ? "/" : path;
     }
 
     @JsxSetter
@@ -321,7 +323,7 @@ public void setPathname(final String path) throws MalformedURLException {
             return;
         }
 
-        url_ = UrlUtils.getUrlWithNewPath(url_, path.startsWith("/") ? path : "/" + path);
+        url_.setPath(path.startsWith("/") ? path : "/" + path);
     }
 
     /**
@@ -344,7 +346,7 @@ public void setPort(final String port) throws MalformedURLException {
             return;
         }
         final int portInt = port.isEmpty() ? -1 : Integer.parseInt(port);
-        url_ = UrlUtils.getUrlWithNewPort(url_, portInt);
+        url_.setPort(portInt);
         checkRemoveRedundantPort();
     }
 
@@ -356,7 +358,7 @@ public String getProtocol() {
         if (url_ == null) {
             return null;
         }
-        final String protocol = url_.getProtocol();
+        final String protocol = url_.getScheme();
         return protocol.isEmpty() ? "" : (protocol + ":");
     }
 
@@ -366,13 +368,8 @@ public void setProtocol(final String protocol) throws MalformedURLException {
             return;
         }
 
-        try {
-            url_ = UrlUtils.getUrlWithNewProtocol(url_, protocol);
-            checkRemoveRedundantPort();
-        }
-        catch (final MalformedURLException e) {
-            // ignore
-        }
+        url_.setScheme(protocol.toLowerCase());
+        checkRemoveRedundantPort();
     }
 
     /**
@@ -383,8 +380,12 @@ public String getSearch() {
         if (url_ == null) {
             return null;
         }
-        final String search = url_.getQuery();
-        return search == null ? "" : "?" + search;
+        final String search = url_.getQueryParams().stream()
+                .map(pair -> pair.getValue() != null
+                        ? String.format("%s=%s", pair.getName(), pair.getValue())
+                        : pair.getName())
+                .collect(Collectors.joining("&"));
+        return StringUtils.isBlank(search) ? "" : "?" + search;
     }
 
     @JsxSetter
@@ -404,7 +405,7 @@ else if (search.charAt(0) == '?') {
             query = search;
         }
 
-        url_ = UrlUtils.getUrlWithNewQuery(url_, query);
+        url_.setQuery(query);
     }
 
     /**
@@ -429,7 +430,7 @@ public void setUsername(final String username) throws MalformedURLException {
         if (url_ == null) {
             return;
         }
-        url_ = UrlUtils.getUrlWithNewUserName(url_, username.isEmpty() ? null : username);
+        url_.setUserInfo(UrlUtils.getUserInfoWithNewUserName(url_.getUserInfo(), username));
     }
 
     /**
@@ -445,9 +446,9 @@ public Object getDefaultValue(final Class<?> hint) {
         }
 
         if (StringUtils.isEmpty(url_.getPath())) {
-            return url_.toExternalForm() + "/";
+            return url_.toString() + "/";
         }
-        return url_.toExternalForm();
+        return url_.toString();
     }
 
     /**
@@ -467,12 +468,11 @@ public String toJSON() {
     public String jsToString() {
         if (StringUtils.isEmpty(url_.getPath())) {
             try {
-                return UrlUtils.getUrlWithNewPath(url_, "/").toExternalForm();
-            }
-            catch (final MalformedURLException e) {
-                return url_.toExternalForm();
+                return UrlUtils.getUrlWithNewPath(url_.build().toURL(), "/").toExternalForm();
+            } catch (final URISyntaxException | MalformedURLException e) {
+                return url_.toString();
             }
         }
-        return url_.toExternalForm();
+        return url_.toString();
     }
 }
diff --git a/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParams.java b/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParams.java
index e3202f3502c..45a25111e05 100644
--- a/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParams.java
+++ b/src/main/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParams.java
@@ -20,13 +20,17 @@
 import static com.gargoylesoftware.htmlunit.javascript.configuration.SupportedBrowser.FF;
 import static com.gargoylesoftware.htmlunit.javascript.configuration.SupportedBrowser.FF78;
 
+import java.net.URISyntaxException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.ListIterator;
+import java.util.stream.Collectors;
 
 import org.apache.commons.lang3.StringUtils;
+import org.apache.http.NameValuePair;
+import org.apache.http.client.utils.URIBuilder;
 import org.apache.http.client.utils.URLEncodedUtils;
 
 import com.gargoylesoftware.htmlunit.FormEncodingType;
@@ -35,7 +39,6 @@
 import com.gargoylesoftware.htmlunit.javascript.configuration.JsxClass;
 import com.gargoylesoftware.htmlunit.javascript.configuration.JsxConstructor;
 import com.gargoylesoftware.htmlunit.javascript.configuration.JsxFunction;
-import com.gargoylesoftware.htmlunit.util.NameValuePair;
 
 import net.sourceforge.htmlunit.corejs.javascript.Context;
 import net.sourceforge.htmlunit.corejs.javascript.ES6Iterator;
@@ -106,12 +109,17 @@ protected Object nextValue(final Context cx, final Scriptable scope) {
         }
     }
 
-    private final List<NameValuePair> params_ = new ArrayList<>();
+    private final URIBuilder url;
 
     /**
      * Constructs a new instance.
      */
     public URLSearchParams() {
+        try {
+            this.url = new URIBuilder("http://dummy.com");
+        } catch (URISyntaxException e) {
+            throw new IllegalStateException("Unexpected");
+        }
     }
 
     /**
@@ -120,6 +128,7 @@ public URLSearchParams() {
      */
     @JsxConstructor
     public URLSearchParams(final Object params) {
+        this();
         // TODO: Pass in a sequence
         // new URLSearchParams([["foo", 1],["bar", 2]]);
 
@@ -130,23 +139,30 @@ public URLSearchParams(final Object params) {
             return;
         }
 
-        splitQuery(Context.toString(params));
+        List<NameValuePair> nameValuePairs = splitQuery(Context.toString(params));
+        url.setParameters(nameValuePairs);
+    }
+
+    public URLSearchParams(final URIBuilder url){
+        this.url = url;
     }
 
-    private void splitQuery(String params) {
+    private List<NameValuePair> splitQuery(String params) {
+        List<NameValuePair> result= new ArrayList<>();
         params = StringUtils.stripStart(params, "?");
         if (StringUtils.isEmpty(params)) {
-            return;
+            return result;
         }
 
         // TODO: encoding
         final String[] parts = StringUtils.split(params, '&');
         for (final String part : parts) {
-            params_.add(splitQueryParameter(part));
+            result.add(splitQueryParameter(part));
         }
+        return result;
     }
 
-    private static NameValuePair splitQueryParameter(final String singleParam) {
+    private static com.gargoylesoftware.htmlunit.util.NameValuePair splitQueryParameter(final String singleParam) {
         final int idx = singleParam.indexOf('=');
         if (idx > -1) {
             final String key = singleParam.substring(0, idx);
@@ -154,13 +170,17 @@ private static NameValuePair splitQueryParameter(final String singleParam) {
             if (idx < singleParam.length()) {
                 value = singleParam.substring(idx + 1);
             }
-            return new NameValuePair(key, value);
+            return new com.gargoylesoftware.htmlunit.util.NameValuePair(key, value);
         }
         final String key = singleParam;
         final String value = "";
-        return new NameValuePair(key, value);
+        return new com.gargoylesoftware.htmlunit.util.NameValuePair(key, value);
     }
 
+    private List<org.apache.http.NameValuePair> getParams() {
+        return url.getQueryParams();
+    }
+    
     /**
      * The append() method of the URLSearchParams interface appends a specified
      * key/value pair as a new search parameter.
@@ -170,7 +190,7 @@ private static NameValuePair splitQueryParameter(final String singleParam) {
      */
     @JsxFunction
     public void append(final String name, final String value) {
-        params_.add(new NameValuePair(name, value));
+        url.addParameter(name, value);
     }
 
     /**
@@ -182,13 +202,15 @@ public void append(final String name, final String value) {
     @JsxFunction
     @Override
     public void delete(final String name) {
-        final Iterator<NameValuePair> iter = params_.iterator();
+        List<NameValuePair> params = url.getQueryParams();
+        final Iterator<NameValuePair> iter = params.iterator();
         while (iter.hasNext()) {
             final NameValuePair entry = iter.next();
             if (entry.getName().equals(name)) {
                 iter.remove();
             }
         }
+        url.setParameters(params);
     }
 
     /**
@@ -200,7 +222,7 @@ public void delete(final String name) {
      */
     @JsxFunction
     public String get(final String name) {
-        for (final NameValuePair param : params_) {
+        for (final NameValuePair param : getParams()) {
             if (param.getName().equals(name)) {
                 return param.getValue();
             }
@@ -217,8 +239,8 @@ public String get(final String name) {
      */
     @JsxFunction
     public Scriptable getAll(final String name) {
-        final List<String> result = new ArrayList<>(params_.size());
-        for (final NameValuePair param : params_) {
+        final List<String> result = new ArrayList<>(getParams().size());
+        for (final NameValuePair param : getParams()) {
             if (param.getName().equals(name)) {
                 result.add(param.getValue());
             }
@@ -238,14 +260,15 @@ public Scriptable getAll(final String name) {
      */
     @JsxFunction
     public void set(final String name, final String value) {
-        boolean change = true;
-        final ListIterator<NameValuePair> iter = params_.listIterator();
+        List<NameValuePair> params = url.getQueryParams();
+        boolean found = false;
+        final ListIterator<NameValuePair> iter = params.listIterator();
         while (iter.hasNext()) {
             final NameValuePair entry = iter.next();
             if (entry.getName().equals(name)) {
-                if (change) {
-                    iter.set(new NameValuePair(name, value));
-                    change = false;
+                if (!found) {
+                    iter.set(new com.gargoylesoftware.htmlunit.util.NameValuePair(name, value));
+                    found = true;
                 }
                 else {
                     iter.remove();
@@ -253,7 +276,9 @@ public void set(final String name, final String value) {
             }
         }
 
-        if (change) {
+        if (found) {
+            url.setParameters(params);
+        } else {
             append(name, value);
         }
     }
@@ -267,7 +292,7 @@ public void set(final String name, final String value) {
      */
     @JsxFunction
     public boolean has(final String name) {
-        for (final NameValuePair param : params_) {
+        for (final NameValuePair param : getParams()) {
             if (param.getName().equals(name)) {
                 return true;
             }
@@ -286,11 +311,11 @@ public boolean has(final String name) {
     public Object entries() {
         if (getBrowserVersion().hasFeature(JS_URL_SEARCH_PARMS_ITERATOR_SIMPLE_NAME)) {
             return new NativeParamsIterator(getParentScope(),
-                    "Iterator", NativeParamsIterator.Type.BOTH, params_.iterator());
+                    "Iterator", NativeParamsIterator.Type.BOTH, getParams().iterator());
         }
 
         return new NativeParamsIterator(getParentScope(),
-                "URLSearchParams Iterator", NativeParamsIterator.Type.BOTH, params_.iterator());
+                "URLSearchParams Iterator", NativeParamsIterator.Type.BOTH, getParams().iterator());
     }
 
     /**
@@ -303,11 +328,11 @@ public Object entries() {
     public Object keys() {
         if (getBrowserVersion().hasFeature(JS_URL_SEARCH_PARMS_ITERATOR_SIMPLE_NAME)) {
             return new NativeParamsIterator(getParentScope(),
-                    "Iterator", NativeParamsIterator.Type.KEYS, params_.iterator());
+                    "Iterator", NativeParamsIterator.Type.KEYS, getParams().iterator());
         }
 
         return new NativeParamsIterator(getParentScope(),
-                "URLSearchParams Iterator", NativeParamsIterator.Type.KEYS, params_.iterator());
+                "URLSearchParams Iterator", NativeParamsIterator.Type.KEYS, getParams().iterator());
     }
 
     /**
@@ -320,11 +345,11 @@ public Object keys() {
     public Object values() {
         if (getBrowserVersion().hasFeature(JS_URL_SEARCH_PARMS_ITERATOR_SIMPLE_NAME)) {
             return new NativeParamsIterator(getParentScope(),
-                    "Iterator", NativeParamsIterator.Type.VALUES, params_.iterator());
+                    "Iterator", NativeParamsIterator.Type.VALUES, getParams().iterator());
         }
 
         return new NativeParamsIterator(getParentScope(),
-                "URLSearchParams Iterator", NativeParamsIterator.Type.VALUES, params_.iterator());
+                "URLSearchParams Iterator", NativeParamsIterator.Type.VALUES, getParams().iterator());
     }
 
     /**
@@ -333,7 +358,15 @@ public Object values() {
      */
     @JsxFunction(functionName = "toString")
     public String jsToString() {
-        return URLEncodedUtils.format(NameValuePair.toHttpClient(params_), "UTF-8");
+        List<NameValuePair> params = getParams().stream()
+                .map(p -> {
+                    if (p.getValue() != null) {
+                        return p;
+                    } else {
+                        return new com.gargoylesoftware.htmlunit.util.NameValuePair(p.getName(), "");
+                    }
+                }).collect(Collectors.toList());
+        return URLEncodedUtils.format(params, "UTF-8");
     }
 
     /**
@@ -355,10 +388,10 @@ public void fillRequest(final WebRequest webRequest) {
         webRequest.setRequestBody(null);
         webRequest.setEncodingType(FormEncodingType.URL_ENCODED);
 
-        if (params_.size() > 0) {
-            final List<NameValuePair> params = new ArrayList<NameValuePair>();
-            for (final NameValuePair entry : params_) {
-                params.add(new NameValuePair(entry.getName(), entry.getValue()));
+        if (getParams().size() > 0) {
+            final List<com.gargoylesoftware.htmlunit.util.NameValuePair> params = new ArrayList<>();
+            for (final NameValuePair entry : getParams()) {
+                params.add(new com.gargoylesoftware.htmlunit.util.NameValuePair(entry.getName(), entry.getValue()));
             }
             webRequest.setRequestParameters(params);
         }
diff --git a/src/main/java/com/gargoylesoftware/htmlunit/util/NameValuePair.java b/src/main/java/com/gargoylesoftware/htmlunit/util/NameValuePair.java
index 5c3b6a15087..b1e19023b2d 100644
--- a/src/main/java/com/gargoylesoftware/htmlunit/util/NameValuePair.java
+++ b/src/main/java/com/gargoylesoftware/htmlunit/util/NameValuePair.java
@@ -28,7 +28,7 @@
  * @author Nicolas Belisle
  * @author Ronald Brill
  */
-public class NameValuePair implements Serializable {
+public class NameValuePair implements org.apache.http.NameValuePair, Serializable {
 
     /** The name. */
     private final String name_;
@@ -46,6 +46,11 @@ public NameValuePair(final String name, final String value) {
         value_ = value;
     }
 
+    public NameValuePair(final org.apache.http.NameValuePair httpPair) {
+        name_ = httpPair.getName();
+        value_ = httpPair.getValue();
+    }
+
     /**
      * Returns the name.
      * @return the name
diff --git a/src/main/java/com/gargoylesoftware/htmlunit/util/UrlUtils.java b/src/main/java/com/gargoylesoftware/htmlunit/util/UrlUtils.java
index 88ed9e0105d..1c65c2f73a7 100644
--- a/src/main/java/com/gargoylesoftware/htmlunit/util/UrlUtils.java
+++ b/src/main/java/com/gargoylesoftware/htmlunit/util/UrlUtils.java
@@ -529,18 +529,27 @@ public static URL getUrlWithProtocolAndAuthority(final URL u) throws MalformedUR
      * @throws MalformedURLException if there is a problem creating the new URL
      */
     public static URL getUrlWithNewUserName(final URL u, final String newUserName) throws MalformedURLException {
+        String newUserInfo = getUserInfoWithNewUserName(u.getUserInfo(), newUserName);
+        return createNewUrl(u.getProtocol(), newUserInfo,
+                u.getHost(), u.getPort(), u.getPath(), u.getRef(), u.getQuery());
+    }
+
+    /**
+     * Creates and returns a new UserInfo identical to the specified UserInfo but with a changed user name.
+     * @param userInfo the UserInfo on which to base the returned URL
+     * @param newUserName the new user name or null to remove it
+     * @return a new UserInfo identical to the specified UserInfo, only user name updated, or null if empty UserInfo
+     */
+    public static String getUserInfoWithNewUserName(final String userInfo, final String newUserName){
         String newUserInfo = newUserName == null ? "" : newUserName;
-        final String userInfo = u.getUserInfo();
         if (org.apache.commons.lang3.StringUtils.isNotBlank(userInfo)) {
             final int colonIdx = userInfo.indexOf(':');
             if (colonIdx > -1) {
                 newUserInfo = newUserInfo + userInfo.substring(colonIdx);
             }
         }
-        return createNewUrl(u.getProtocol(), newUserInfo.isEmpty() ? null : newUserInfo,
-                u.getHost(), u.getPort(), u.getPath(), u.getRef(), u.getQuery());
+        return newUserInfo.isEmpty() ? null : newUserInfo;
     }
-
     /**
      * Creates and returns a new URL identical to the specified URL but with a changed user password.
      * @param u the URL on which to base the returned URL
@@ -550,8 +559,19 @@ public static URL getUrlWithNewUserName(final URL u, final String newUserName) t
      */
     public static URL getUrlWithNewUserPassword(final URL u, final String newUserPassword)
             throws MalformedURLException {
+        String newUserInfo = getUserInfoWithNewUserPassword(u.getUserInfo(), newUserPassword);
+        return createNewUrl(u.getProtocol(), newUserInfo,
+                u.getHost(), u.getPort(), u.getPath(), u.getRef(), u.getQuery());
+    }
+
+    /**
+     * Creates and returns a new UserInfo identical to the specified UserInfo but with a changed user password.
+     * @param userInfo the UserInfo on which to base the returned UserInfo
+     * @param newUserPassword the new user password or null to remove it
+     * @return a new UserInfo identical to the specified URL, only user name updated, or null if empty UserInfo
+     */
+    public static String getUserInfoWithNewUserPassword(final String userInfo, final String newUserPassword) {
         String newUserInfo = newUserPassword == null ? "" : (':' + newUserPassword);
-        final String userInfo = u.getUserInfo();
         if (org.apache.commons.lang3.StringUtils.isNotBlank(userInfo)) {
             final int colonIdx = userInfo.indexOf(':');
             if (colonIdx > -1) {
@@ -561,8 +581,7 @@ public static URL getUrlWithNewUserPassword(final URL u, final String newUserPas
                 newUserInfo = userInfo + newUserInfo;
             }
         }
-        return createNewUrl(u.getProtocol(), newUserInfo.isEmpty() ? null : newUserInfo,
-                u.getHost(), u.getPort(), u.getPath(), u.getRef(), u.getQuery());
+        return newUserInfo.isEmpty() ? null : newUserInfo;
     }
 
     /**
diff --git a/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParamsTest.java b/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParamsTest.java
index 76879e8c08e..e43a0fe0edf 100644
--- a/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParamsTest.java
+++ b/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLSearchParamsTest.java
@@ -371,6 +371,11 @@ public void getAll() throws Exception {
      */
     @Test
     @Alerts(DEFAULT = {"key1=val1&key2=val2&key2=val3&key4=val4",
+                       "key1=new1&key2=val2&key2=val3&key4=val4",
+                       "key1=new1&key2=new2&key4=val4",
+                       "key1=new1&key2=new2&key4=val4&key3=undefined",
+                       "key1=new1&key2=new2&key4=null&key3=undefined",
+                       "key1=val1&key2=val2&key2=val3&key4=val4",
                        "key1=new1&key2=val2&key2=val3&key4=val4",
                        "key1=new1&key2=new2&key4=val4",
                        "key1=new1&key2=new2&key4=val4&key3=undefined",
@@ -437,6 +442,17 @@ public void setFromUrl() throws Exception {
             + "        log(param);\n"
             + "        param.set('key4', null);\n"
             + "        log(param);\n"
+            + "        param = new URL('http://test.com/p?key1=val1&key2=val2&key2=val3').searchParams;\n"
+            + "        param.set('key4', 'val4');\n"
+            + "        log(param);\n"
+            + "        param.set('key1', 'new1');\n"
+            + "        log(param);\n"
+            + "        param.set('key2', 'new2');\n"
+            + "        log(param);\n"
+            + "        param.set('key3', undefined);\n"
+            + "        log(param);\n"
+            + "        param.set('key4', null);\n"
+            + "        log(param);\n"
             + "      }\n"
             + "    }\n"
             + "  </script>\n"
diff --git a/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLTest.java b/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLTest.java
index e2eea52f6ff..583acc7ec54 100644
--- a/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLTest.java
+++ b/src/test/java/com/gargoylesoftware/htmlunit/javascript/host/URLTest.java
@@ -185,7 +185,7 @@ public void createObjectURL() throws Exception {
      * @throws Exception if an error occurs
      */
     @Test
-    @Alerts(DEFAULT = {"", "a=u&x="},
+    @Alerts(DEFAULT = {"", "a=u&x=", "a=b&x=", "x=", "x=&b=c"},
             IE = {})
     public void searchParams() throws Exception {
         final String html =
@@ -199,6 +199,13 @@ public void searchParams() throws Exception {
             + "        log(u.searchParams);\n"
             + "        u = new URL('http://developer.mozilla.org/en-US/docs?a=u&x');\n"
             + "        log(u.searchParams);\n"
+            + "        var params = u.searchParams;\n"
+            + "        params.set('a','b');\n"
+            + "        log(params);\n"
+            + "        params.delete('a');\n"
+            + "        log(params);\n"
+            + "        params.append('b', 'c');\n"
+            + "        log(params);\n"
             + "      }\n"
             + "    }\n"
             + "  </script>\n"