diff --git a/src/java/org/apache/nutch/util/URLUtil.java b/src/java/org/apache/nutch/util/URLUtil.java
index fd036480a6..c921041ca3 100644
--- a/src/java/org/apache/nutch/util/URLUtil.java
+++ b/src/java/org/apache/nutch/util/URLUtil.java
@@ -24,6 +24,7 @@
 import java.util.Locale;
 import java.util.regex.Pattern;
 
+import com.ibm.icu.util.ICUException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -675,11 +676,23 @@ public static String convertIDNA2008(String host, boolean toAscii)
       throws MalformedURLException {
     final IDNA.Info idnaInfo = new IDNA.Info();
     final StringBuilder hostConverted = new StringBuilder();
-    if (toAscii) {
-      idna.nameToASCII(host, hostConverted, idnaInfo);
-    } else {
-      idna.nameToUnicode(host, hostConverted, idnaInfo);
+    try {
+      if (toAscii) {
+        idna.nameToASCII(host, hostConverted, idnaInfo);
+      } else {
+        idna.nameToUnicode(host, hostConverted, idnaInfo);
+      }
+    } catch (ICUException | IllegalArgumentException | IllegalStateException e) {
+      // ICU's UTS46 + Punycode conversion throws these unchecked exceptions:
+      // ICUException (incl. ICUInputTooLongException from Punycode.encode on an
+      // over-long label), IllegalArgumentException (UTS46), IllegalStateException
+      // (Punycode). Convert to MalformedURLException so callers (e.g.
+      // BasicURLNormalizer) reject the URL instead of crashing the task.
+      LOG.debug("Failed to convert IDN host {}: ", host, e);
+      throw (MalformedURLException) new MalformedURLException(
+          "Invalid IDN host " + host + ": " + e.getMessage()).initCause(e);
     }
+
     if (idnaInfo.hasErrors()) {
       StringBuilder msg = new StringBuilder();
       for (IDNA.Error error : idnaInfo.getErrors()) {
diff --git a/src/test/org/apache/nutch/util/TestURLUtil.java b/src/test/org/apache/nutch/util/TestURLUtil.java
index 573af66430..5cd4028789 100644
--- a/src/test/org/apache/nutch/util/TestURLUtil.java
+++ b/src/test/org/apache/nutch/util/TestURLUtil.java
@@ -24,6 +24,8 @@
 
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.net.URLDecoder;
+import java.util.Locale;
 
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -446,6 +448,18 @@ public final void testConvertHostInvalid() {
         () -> URLUtil.convertIDNA2008("xn--a-ä.pt", true));
   }
 
+  @Test
+  public void testConvertHostInvalidFromJuneCrawl() throws MalformedURLException {
+    // Goodies from the June Crawl 2026
+    String url = "http://techsauce%20global%20summit%202023%20%E0%B9%80%E0%B8%9B%E0%B9%87%E0%B8%99%E0%B8%87%E0%B8%B2%E0%B8%99%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B8%8A%E0%B8%B8%E0%B8%A1%E0%B8%A3%E0%B8%B0%E0%B8%94%E0%B8%B1%E0%B8%9A%E0%B9%82%E0%B8%A5%E0%B8%81%E0%B8%97%E0%B8%B5%E0%B9%88%E0%B8%88%E0%B8%B1%E0%B8%94%E0%B8%82%E0%B8%B6%E0%B9%89%E0%B8%99%E0%B9%83%E0%B8%99%E0%B8%A7%E0%B8%B1%E0%B8%99%E0%B8%97%E0%B8%B5%E0%B9%88%2016%E2%80%9317%20%E0%B8%AA%E0%B8%B4%E0%B8%87%E0%B8%AB%E0%B8%B2%E0%B8%84%E0%B8%A1%202566%20%E0%B8%93%20%E0%B8%A8%E0%B8%B9%E0%B8%99%E0%B8%A2%E0%B9%8C%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B8%8A%E0%B8%B8%E0%B8%A1%E0%B9%81%E0%B8%AB%E0%B9%88%E0%B8%87%E0%B8%8A%E0%B8%B2%E0%B8%95%E0%B8%B4%E0%B8%AA%E0%B8%B4%E0%B8%A3%E0%B8%B4%E0%B8%81%E0%B8%B4%E0%B8%95%E0%B8%B4%E0%B9%8C%20%E0%B8%81%E0%B8%A3%E0%B8%B8%E0%B8%87%E0%B9%80%E0%B8%97%E0%B8%9E%E0%B8%AF%20%E0%B8%87%E0%B8%B2%E0%B8%99%E0%B8%99%E0%B8%B5%E0%B9%89%E0%B8%94%E0%B8%B6%E0%B8%87%E0%B8%94%E0%B8%B9%E0%B8%94%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B9%80%E0%B8%82%E0%B9%89%E0%B8%B2%E0%B8%A3%E0%B9%88%E0%B8%A7%E0%B8%A1%E0%B8%87%E0%B8%B2%E0%B8%99%E0%B8%88%E0%B8%B2%E0%B8%81%E0%B8%81%E0%B8%A7%E0%B9%88%E0%B8%B2%2050%20%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B9%80%E0%B8%97%E0%B8%A8%20%E0%B9%82%E0%B8%94%E0%B8%A2%E0%B8%A1%E0%B8%B5%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B9%80%E0%B8%82%E0%B9%89%E0%B8%B2%E0%B8%A3%E0%B9%88%E0%B8%A7%E0%B8%A1%E0%B8%87%E0%B8%B2%E0%B8%99%E0%B8%A1%E0%B8%B2%E0%B8%81%E0%B8%81%E0%B8%A7%E0%B9%88%E0%B8%B2%2016,000%20%E0%B8%84%E0%B8%99%20%E0%B9%81%E0%B8%A5%E0%B8%B0%E0%B8%A1%E0%B8%B5%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B9%80%E0%B8%82%E0%B9%89%E0%B8%B2%E0%B8%A3%E0%B9%88%E0%B8%A7%E0%B8%A1%E0%B8%88%E0%B8%B2%E0%B8%81%E0%B8%99%E0%B8%B2%E0%B8%99%E0%B8%B2%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B9%80%E0%B8%97%E0%B8%A8%E0%B8%A1%E0%B8%B2%E0%B8%81%E0%B8%96%E0%B8%B6%E0%B8%87%2040%25%20%20%E0%B9%83%E0%B8%99%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B8%88%E0%B8%B1%E0%B8%94%E0%B8%87%E0%B8%B2%E0%B8%99%E0%B8%84%E0%B8%A3%E0%B8%B1%E0%B9%89%E0%B8%87%E0%B8%99%E0%B8%B5%E0%B9%89%20%E0%B8%A1%E0%B8%B5%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B8%99%E0%B8%B3%E0%B9%80%E0%B8%AA%E0%B8%99%E0%B8%AD%E0%B8%88%E0%B8%B2%E0%B8%81%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B8%9A%E0%B8%A3%E0%B8%A3%E0%B8%A2%E0%B8%B2%E0%B8%A2%E0%B8%8A%E0%B8%B1%E0%B9%89%E0%B8%99%E0%B8%99%E0%B8%B3%20%E0%B8%A3%E0%B8%A7%E0%B8%A1%E0%B8%96%E0%B8%B6%E0%B8%87%E0%B9%82%E0%B8%8B%E0%B8%99%20business%20matching%20%E0%B8%97%E0%B8%B5%E0%B9%88%E0%B9%80%E0%B8%95%E0%B9%87%E0%B8%A1%E0%B9%84%E0%B8%9B%E0%B8%94%E0%B9%89%E0%B8%A7%E0%B8%A2%E0%B9%82%E0%B8%AD%E0%B8%81%E0%B8%B2%E0%B8%AA%E0%B8%AA%E0%B8%B3%E0%B8%AB%E0%B8%A3%E0%B8%B1%E0%B8%9A%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B8%9B%E0%B8%A3%E0%B8%B0%E0%B8%81%E0%B8%AD%E0%B8%9A%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B8%88%E0%B8%B2%E0%B8%81%E0%B8%AD%E0%B8%87%E0%B8%84%E0%B9%8C%E0%B8%81%E0%B8%A3%E0%B8%8A%E0%B8%B1%E0%B9%89%E0%B8%99%E0%B8%99%E0%B8%B3%20%E0%B8%AA%E0%B8%95%E0%B8%B2%E0%B8%A3%E0%B9%8C%E0%B8%97%E0%B8%AD%E0%B8%B1%E0%B8%9E%20smes%20%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B9%80%E0%B8%8A%E0%B8%B5%E0%B9%88%E0%B8%A2%E0%B8%A7%E0%B8%8A%E0%B8%B2%E0%B8%8D%E0%B8%94%E0%B9%89%E0%B8%B2%E0%B8%99%E0%B9%80%E0%B8%97%E0%B8%84%E0%B9%82%E0%B8%99%E0%B9%82%E0%B8%A5%E0%B8%A2%E0%B8%B5%20%E0%B9%81%E0%B8%A5%E0%B8%B0%E0%B8%9A%E0%B8%B8%E0%B8%84%E0%B8%84%E0%B8%A5%E0%B8%97%E0%B8%B1%E0%B9%88%E0%B8%A7%E0%B9%84%E0%B8%9B%20%E0%B9%80%E0%B8%9E%E0%B8%B7%E0%B9%88%E0%B8%AD%E0%B9%81%E0%B8%A5%E0%B8%81%E0%B9%80%E0%B8%9B%E0%B8%A5%E0%B8%B5%E0%B9%88%E0%B8%A2%E0%B8%99%E0%B8%84%E0%B8%A7%E0%B8%B2%E0%B8%A1%E0%B8%84%E0%B8%B4%E0%B8%94%E0%B9%80%E0%B8%AB%E0%B9%87%E0%B8%99%E0%B8%97%E0%B8%B2%E0%B8%87%E0%B8%98%E0%B8%B8%E0%B8%A3%E0%B8%81%E0%B8%B4%E0%B8%88%20%E0%B9%82%E0%B8%94%E0%B8%A2%E0%B8%97%E0%B8%B1%E0%B9%89%E0%B8%87%E0%B8%AB%E0%B8%A1%E0%B8%94%E0%B8%99%E0%B8%B5%E0%B9%89%E0%B9%84%E0%B8%94%E0%B9%89%E0%B8%AA%E0%B8%A3%E0%B9%89%E0%B8%B2%E0%B8%87%E0%B9%82%E0%B8%AD%E0%B8%81%E0%B8%B2%E0%B8%AA%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B8%97%E0%B8%B3%E0%B8%98%E0%B8%B8%E0%B8%A3%E0%B8%81%E0%B8%B4%E0%B8%88%E0%B9%80%E0%B8%9E%E0%B8%B4%E0%B9%88%E0%B8%A1%E0%B8%82%E0%B8%B6%E0%B9%89%E0%B8%99%E0%B8%96%E0%B8%B6%E0%B8%87%201,000%20%E0%B8%84%E0%B8%A3%E0%B8%B1%E0%B9%89%E0%B8%87%20%20%E0%B8%AA%E0%B8%A3%E0%B8%B8%E0%B8%9B%20%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B9%83%E0%B8%8A%E0%B9%89%20nft%20gen2%20%E0%B8%8B%E0%B8%B6%E0%B9%88%E0%B8%87%E0%B9%80%E0%B8%9B%E0%B9%87%E0%B8%99%E0%B8%AA%E0%B9%88%E0%B8%A7%E0%B8%99%E0%B8%AB%E0%B8%99%E0%B8%B6%E0%B9%88%E0%B8%87%E0%B8%82%E0%B8%AD%E0%B8%87%E0%B9%80%E0%B8%97%E0%B8%84%E0%B9%82%E0%B8%99%E0%B9%82%E0%B8%A5%E0%B8%A2%E0%B8%B5%20dynamic%20data%20layer%20%E0%B8%82%E0%B8%AD%E0%B8%87%E0%B8%97%E0%B8%B2%E0%B8%87%20six%20network%20%E0%B8%97%E0%B8%B5%E0%B9%88%E0%B8%87%E0%B8%B2%E0%B8%99%20techsauce%20global%20summit%202023%20%E0%B9%84%E0%B8%94%E0%B9%89%E0%B9%80%E0%B8%9E%E0%B8%B4%E0%B9%88%E0%B8%A1%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B8%A1%E0%B8%B5%E0%B8%AA%E0%B9%88%E0%B8%A7%E0%B8%99%E0%B8%A3%E0%B9%88%E0%B8%A7%E0%B8%A1%E0%B8%82%E0%B8%AD%E0%B8%87%E0%B8%9C%E0%B8%B9%E0%B9%89%E0%B9%83%E0%B8%8A%E0%B9%89%20%E0%B8%94%E0%B9%89%E0%B8%A7%E0%B8%A2%E0%B8%81%E0%B8%B2%E0%B8%A3%E0%B9%80%E0%B8%8A%E0%B8%B7%E0%B9%88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+    URL u = new URL(url);
+    String host = u.getHost();
+    String hostDecoded = java.net.URLDecoder.decode(host, java.nio.charset.StandardCharsets.UTF_8);
+    String hostLowerCase = hostDecoded.toLowerCase(Locale.ROOT);
+    assertThrows(MalformedURLException.class,
+        () -> URLUtil.convertIDNA2008(hostLowerCase, true));
+  }
+
   @Test
   public void testFileProtocol() throws Exception {
     // keep one single slash NUTCH-1483