diff --git a/smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java b/smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java
index eff83268d..883812f59 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/AbstractXMPPConnection.java
@@ -2012,7 +2012,7 @@ public abstract class AbstractXMPPConnection implements XMPPConnection {
             from = XmppStringUtils.completeJidFrom(localpart, to);
         }
         String id = getStreamId();
-        sendNonza(new StreamOpen(to, from, id, config.getXmlLang(), StreamOpen.StreamContentNamespace.client));
+        sendNonza(new StreamOpen(to, from, id));
     }
 
     public static final class SmackTlsContext {
diff --git a/smack-core/src/main/java/org/jivesoftware/smack/ConnectionConfiguration.java b/smack-core/src/main/java/org/jivesoftware/smack/ConnectionConfiguration.java
index e302a1159..730320132 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/ConnectionConfiguration.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/ConnectionConfiguration.java
@@ -24,7 +24,6 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
-import java.util.Locale;
 import java.util.Set;
 import java.util.logging.Level;
 import java.util.logging.Logger;
@@ -119,8 +118,6 @@ public abstract class ConnectionConfiguration {
     private final String password;
     private final Resourcepart resource;
 
-    private final Locale language;
-
     /**
      * The optional SASL authorization identity (see RFC 6120 § 6.3.8).
      */
@@ -168,8 +165,6 @@ public abstract class ConnectionConfiguration {
         // Resource can be null, this means that the server must provide one
         resource = builder.resource;
 
-        language = builder.language;
-
         xmppServiceDomain = builder.xmppServiceDomain;
         if (xmppServiceDomain == null) {
             throw new IllegalArgumentException("Must define the XMPP domain");
@@ -481,34 +476,6 @@ public abstract class ConnectionConfiguration {
         return resource;
     }
 
-    /**
-     * Returns the stream language to use when connecting to the server.
-     *
-     * @return the stream language to use when connecting to the server.
-     */
-    public Locale getLanguage() {
-        return language;
-    }
-
-    /**
-     * Returns the xml:lang string of the stream language to use when connecting to the server.
-     *
-     * <p>If the developer sets the language to null, this will also return null, leading to
-     * the removal of the xml:lang tag from the stream. If a Locale("") is configured, this will
-     * return "", which can be used as an override.</p>
-     *
-     * @return the stream language to use when connecting to the server.
-     */
-    public String getXmlLang() {
-        // TODO: Change to Locale.toLanguageTag() once Smack's minimum Android API level is 21 or higher.
-        // This will need a workaround for new Locale("").getLanguageTag() returning "und". Expected
-        // behavior of this function:
-        //  - returns null if language is null
-        //  - returns "" if language.getLanguage() returns the empty string
-        //  - returns language.toLanguageTag() otherwise
-        return language != null ? language.toString().replace("_", "-") : null;
-    }
-
     /**
      * Returns the optional XMPP address to be requested as the SASL authorization identity.
      *
@@ -597,7 +564,6 @@ public abstract class ConnectionConfiguration {
         private CharSequence username;
         private String password;
         private Resourcepart resource;
-        private Locale language = Locale.getDefault();
         private boolean sendPresence = true;
         private ProxyInfo proxy;
         private CallbackHandler callbackHandler;
@@ -722,19 +688,6 @@ public abstract class ConnectionConfiguration {
             return getThis();
         }
 
-        /**
-         * Set the stream language.
-         *
-         * @param language the language to use.
-         * @return a reference to this builder.
-         * @see <a href="https://tools.ietf.org/html/rfc6120#section-4.7.4">RFC 6120 § 4.7.4</a>
-         * @see <a href="https://www.w3.org/TR/xml/#sec-lang-tag">XML 1.0 § 2.12 Language Identification</a>
-         */
-        public B setLanguage(Locale language) {
-            this.language = language;
-            return getThis();
-        }
-
         /**
          * Set the resource we are requesting from the server.
          *
diff --git a/smack-core/src/main/java/org/jivesoftware/smack/util/XmlStringBuilder.java b/smack-core/src/main/java/org/jivesoftware/smack/util/XmlStringBuilder.java
index 4f0b93680..56e6eb177 100644
--- a/smack-core/src/main/java/org/jivesoftware/smack/util/XmlStringBuilder.java
+++ b/smack-core/src/main/java/org/jivesoftware/smack/util/XmlStringBuilder.java
@@ -112,7 +112,7 @@ public class XmlStringBuilder implements Appendable, CharSequence, Element {
 
     public XmlStringBuilder element(String name, Enum<?> content) {
         assert content != null;
-        element(name, content.toString());
+        element(name, content.name());
         return this;
     }
 
diff --git a/smack-extensions/src/test/java/org/jivesoftware/smackx/muc/MucMemoryLeakTest.java b/smack-extensions/src/test/java/org/jivesoftware/smackx/muc/MucMemoryLeakTest.java
index d9e35fefd..ad7c24ebd 100644
--- a/smack-extensions/src/test/java/org/jivesoftware/smackx/muc/MucMemoryLeakTest.java
+++ b/smack-extensions/src/test/java/org/jivesoftware/smackx/muc/MucMemoryLeakTest.java
@@ -19,14 +19,12 @@ package org.jivesoftware.smackx.muc;
 import org.jivesoftware.smack.test.util.SmackTestSuite;
 import org.jivesoftware.smack.util.MemoryLeakTestUtil;
 
-import org.junit.jupiter.api.Disabled;
-import org.junit.jupiter.api.Test;
+import org.junit.Test;
 import org.jxmpp.stringprep.XmppStringprepException;
 
 public class MucMemoryLeakTest extends SmackTestSuite {
 
     @Test
-    @Disabled
     public void mucMemoryLeakTest() throws XmppStringprepException, IllegalArgumentException, InterruptedException {
         MemoryLeakTestUtil.noResourceLeakTest(c -> MultiUserChatManager.getInstanceFor(c));
     }