diff --git a/src/java.base/share/classes/java/util/JapaneseImperialCalendar.java b/src/java.base/share/classes/java/util/JapaneseImperialCalendar.java
index d275b09834ab8..755fe1133f5da 100644
--- a/src/java.base/share/classes/java/util/JapaneseImperialCalendar.java
+++ b/src/java.base/share/classes/java/util/JapaneseImperialCalendar.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1856,6 +1856,14 @@ protected void computeTime() {
 
         if (isSet(ERA)) {
             era = internalGet(ERA);
+            // Don't check under, historically we have allowed values under
+            // BEFORE_MEIJI to be ignored during normalization
+            // We check against eras.length (not the highest constant ERA value)
+            // due to future added eras, or additional eras via
+            // "jdk.calendar.japanese.supplemental.era"
+            if (era >= eras.length) {
+                throw new IllegalArgumentException("Invalid era");
+            }
             year = isSet(YEAR) ? internalGet(YEAR) : 1;
         } else {
             if (isSet(YEAR)) {
diff --git a/test/jdk/java/util/Calendar/Builder/BuilderTest.java b/test/jdk/java/util/Calendar/Builder/BuilderTest.java
index d74c38c067ac4..34fab9204ed52 100644
--- a/test/jdk/java/util/Calendar/Builder/BuilderTest.java
+++ b/test/jdk/java/util/Calendar/Builder/BuilderTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,8 +23,9 @@
 
 /*
  * @test
- * @bug 4745761
+ * @bug 4745761 8350646
  * @summary Unit test for Calendar.Builder.
+ * @run main BuilderTest
  */
 
 import java.time.LocalDateTime;
@@ -245,6 +246,11 @@ private static void testExceptions() {
         checkException(calb, IllegalArgumentException.class);
         calb = builder().setCalendarType("japanese").setWeekDate(2013, 1, MONDAY);
         checkException(calb, IllegalArgumentException.class);
+        // JDK-8350646 : Ensure IAE (instead of AIOOBE) for ERA over largest supported
+        calb = builder().setCalendarType("japanese").setFields(ERA, 6);
+        checkException(calb, IllegalArgumentException.class);
+        // Note that we don't check ERAs under BEFORE_MEIJI, i.e. -1, -2, ... as
+        // historically JapaneseImperialCalendar ignores such values when normalizing
     }
 
     private static Calendar.Builder builder() {
diff --git a/test/jdk/java/util/Calendar/SupplementalJapaneseEraTest.java b/test/jdk/java/util/Calendar/SupplementalJapaneseEraTest.java
index 010519dc89e1f..411fc528dceef 100644
--- a/test/jdk/java/util/Calendar/SupplementalJapaneseEraTest.java
+++ b/test/jdk/java/util/Calendar/SupplementalJapaneseEraTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -67,6 +67,22 @@ public static void main(String[] args) {
     }
 
     private static void testProperty() {
+        // JDK-8350646: Ensure that IAE is thrown for out of range era, when
+        // additional era is defined
+        try {
+            new Calendar.Builder()
+                    .setCalendarType("japanese")
+                    .setFields(ERA, JapaneseEra.values().length + 2)
+                    .build();
+            System.err.println("Out of range era should have thrown IAE");
+            errors++;
+        } catch (Exception e) {
+            if (!(e instanceof IllegalArgumentException)) {
+                System.err.printf("Out of range era threw \"%s\" instead of IAE\n", e);
+                errors++;
+            }
+        }
+
         Calendar jcal = new Calendar.Builder()
             .setCalendarType("japanese")
             .setFields(ERA, 6, YEAR, 1, DAY_OF_YEAR, 1)
diff --git a/test/jdk/java/util/Calendar/SupplementalJapaneseEraTestRun.java b/test/jdk/java/util/Calendar/SupplementalJapaneseEraTestRun.java
index 5383d0d124055..8eac4a97ef700 100644
--- a/test/jdk/java/util/Calendar/SupplementalJapaneseEraTestRun.java
+++ b/test/jdk/java/util/Calendar/SupplementalJapaneseEraTestRun.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -23,7 +23,7 @@
 
 /*
  * @test
- * @bug 8048123 8054214 8173423
+ * @bug 8048123 8054214 8173423 8350646
  * @summary Test for jdk.calendar.japanese.supplemental.era support
  * @library /test/lib
  * @build SupplementalJapaneseEraTest