diff --git a/backend.native/tests/harmony_regex/PatternSyntaxExceptionTest.kt b/backend.native/tests/harmony_regex/PatternSyntaxExceptionTest.kt
index a53aff5692e..b956e573097 100644
--- a/backend.native/tests/harmony_regex/PatternSyntaxExceptionTest.kt
+++ b/backend.native/tests/harmony_regex/PatternSyntaxExceptionTest.kt
@@ -25,8 +25,8 @@ class PatternSyntaxExceptionTest {
         val regex = "("
         try {
             Regex(regex)
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
             // TODO: Check the exception's properties.
         }
 
@@ -36,8 +36,8 @@ class PatternSyntaxExceptionTest {
         val regex = "[4-"
         try {
             Regex(regex)
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
     }
diff --git a/backend.native/tests/harmony_regex/PatternTest.kt b/backend.native/tests/harmony_regex/PatternTest.kt
index 521336cc5e8..701bb7452ab 100644
--- a/backend.native/tests/harmony_regex/PatternTest.kt
+++ b/backend.native/tests/harmony_regex/PatternTest.kt
@@ -238,32 +238,32 @@ class PatternTest {
         var pattern = "b)a"
         try {
             Regex(pattern)
-            fail("Expected a PatternSyntaxException when compiling pattern: " + pattern)
-        } catch (e: PatternSyntaxException) {
+            fail("Expected a IllegalArgumentException when compiling pattern: " + pattern)
+        } catch (e: IllegalArgumentException) {
             // pass
         }
 
         pattern = "bcde)a"
         try {
             Regex(pattern)
-            fail("Expected a PatternSyntaxException when compiling pattern: " + pattern)
-        } catch (e: PatternSyntaxException) {
+            fail("Expected a IllegalArgumentException when compiling pattern: " + pattern)
+        } catch (e: IllegalArgumentException) {
             // pass
         }
 
         pattern = "bbg())a"
         try {
             Regex(pattern)
-            fail("Expected a PatternSyntaxException when compiling pattern: " + pattern)
-        } catch (e: PatternSyntaxException) {
+            fail("Expected a IllegalArgumentException when compiling pattern: " + pattern)
+        } catch (e: IllegalArgumentException) {
             // pass
         }
 
         pattern = "cdb(?i))a"
         try {
             Regex(pattern)
-            fail("Expected a PatternSyntaxException when compiling pattern: " + pattern)
-        } catch (e: PatternSyntaxException) {
+            fail("Expected a IllegalArgumentException when compiling pattern: " + pattern)
+        } catch (e: IllegalArgumentException) {
             // pass
         }
 
@@ -286,8 +286,8 @@ class PatternTest {
         for (element in patterns) {
             try {
                 Regex(element)
-                fail("PatternSyntaxException was expected, but compilation succeeds")
-            } catch (pse: PatternSyntaxException) {
+                fail("IllegalArgumentException was expected, but compilation succeeds")
+            } catch (pse: IllegalArgumentException) {
                 continue
             }
 
@@ -350,8 +350,8 @@ class PatternTest {
         for (element in neg_patterns) {
             try {
                 Regex(element)
-                fail("PatternSyntaxException was expected: " + element)
-            } catch (pse: PatternSyntaxException) {
+                fail("IllegalArgumentException was expected: " + element)
+            } catch (pse: IllegalArgumentException) {
             }
 
         }
@@ -393,8 +393,8 @@ class PatternTest {
     @Test fun testOrphanQuantifiers() {
         try {
             Regex("+++++")
-            fail("PatternSyntaxException expected")
-        } catch (pse: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (pse: IllegalArgumentException) {
         }
 
     }
@@ -402,8 +402,8 @@ class PatternTest {
     @Test fun testOrphanQuantifiers2() {
         try {
             Regex("\\d+*")
-            fail("PatternSyntaxException expected")
-        } catch (pse: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (pse: IllegalArgumentException) {
         }
 
     }
@@ -561,8 +561,8 @@ class PatternTest {
     @Test fun testIllegalEscape() {
         try {
             Regex("\\y")
-            fail("PatternSyntaxException expected")
-        } catch (pse: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (pse: IllegalArgumentException) {
         }
     }
 
@@ -742,7 +742,7 @@ class PatternTest {
             Regex("(?:)", setOf(RegexOption.CANON_EQ, RegexOption.IGNORE_CASE))
             Regex("(?:)", setOf(RegexOption.CANON_EQ, RegexOption.COMMENTS, RegexOption.UNIX_LINES))
             isCompiled = true
-        } catch (e: PatternSyntaxException) {
+        } catch (e: IllegalArgumentException) {
             println(e)
         }
         assertTrue(isCompiled)
diff --git a/backend.native/tests/harmony_regex/PatternTest2.kt b/backend.native/tests/harmony_regex/PatternTest2.kt
index 2658b676eb6..d72877b7bef 100644
--- a/backend.native/tests/harmony_regex/PatternTest2.kt
+++ b/backend.native/tests/harmony_regex/PatternTest2.kt
@@ -95,7 +95,7 @@ class PatternTest2 {
             assertNotNull(result)
             assertEquals(6, result!!.range.start)
             assertEquals(9, result.range.endInclusive + 1)
-        } catch (e: PatternSyntaxException) {
+        } catch (e: IllegalArgumentException) {
             println(e.message)
             fail()
         }
@@ -249,51 +249,51 @@ class PatternTest2 {
         // Test invalid unicode sequences // TODO: Double check it.
         try {
             regex = Regex("\\u")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\u;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\u002")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\u002;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         // Test invalid hex sequences
         try {
             regex = Regex("\\x")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\x;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\xa")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\xa;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         // Test \0 (octal) sequences (1, 2 and 3 digit)
@@ -312,20 +312,20 @@ class PatternTest2 {
         // Test invalid octal sequences
         try {
             regex = Regex("\\08")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\0")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\0;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         // Test \c (control character) sequence
@@ -364,8 +364,8 @@ class PatternTest2 {
         // Test invalid control escapes
         try {
             regex = Regex("\\c")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
     }
 
@@ -456,8 +456,8 @@ class PatternTest2 {
 
         try {
             regex = Regex("[[abc]&&")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         regex = Regex("[[abc]\\&&[xyz]]")
@@ -561,38 +561,38 @@ class PatternTest2 {
         // Invalid uses of \p{Lower}
         try {
             regex = Regex("\\p")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\p;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\p{")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\p{;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\p{Lower")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\p{Lower;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         // Test \p{Upper}
@@ -608,14 +608,14 @@ class PatternTest2 {
         // Invalid uses of \p{Upper}
         try {
             regex = Regex("\\p{Upper")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\p{Upper;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         // Test \p{ASCII}
@@ -636,14 +636,14 @@ class PatternTest2 {
         // Invalid uses of \p{ASCII}
         try {
             regex = Regex("\\p{ASCII")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         try {
             regex = Regex("\\p{ASCII;")
-            fail("PatternSyntaxException expected")
-        } catch (e: PatternSyntaxException) {
+            fail("IllegalArgumentException expected")
+        } catch (e: IllegalArgumentException) {
         }
 
         // Test \p{Alpha}