diff --git a/hibernate-core/src/main/java/org/hibernate/dialect/function/array/JsonArrayViaElementArgumentReturnTypeResolver.java b/hibernate-core/src/main/java/org/hibernate/dialect/function/array/JsonArrayViaElementArgumentReturnTypeResolver.java
index 3aa6e0255078..da1b97d26276 100644
--- a/hibernate-core/src/main/java/org/hibernate/dialect/function/array/JsonArrayViaElementArgumentReturnTypeResolver.java
+++ b/hibernate-core/src/main/java/org/hibernate/dialect/function/array/JsonArrayViaElementArgumentReturnTypeResolver.java
@@ -84,9 +84,7 @@ public static <T> BasicType<?> resolveJsonArrayType(DomainType<T> elementType, T
 		final Class<?> arrayClass = Array.newInstance( elementType.getJavaType(), 0 ).getClass();
 		@SuppressWarnings("unchecked")
 		final BasicPluralJavaType<T> arrayJavaType =
-				(BasicPluralJavaType<T>)
-						typeConfiguration.getJavaTypeRegistry()
-								.getDescriptor( arrayClass );
+				(BasicPluralJavaType<T>) typeConfiguration.getJavaTypeRegistry().getDescriptor( arrayClass );
 		final JdbcTypeIndicators currentBaseSqlTypeIndicators = typeConfiguration.getCurrentBaseSqlTypeIndicators();
 		return arrayJavaType.resolveType(
 				typeConfiguration,
@@ -96,7 +94,12 @@ public static <T> BasicType<?> resolveJsonArrayType(DomainType<T> elementType, T
 				new DelegatingJdbcTypeIndicators( currentBaseSqlTypeIndicators ) {
 					@Override
 					public Integer getExplicitJdbcTypeCode() {
-						return SqlTypes.JSON;
+						return SqlTypes.JSON_ARRAY;
+					}
+
+					@Override
+					public  int getPreferredSqlTypeCodeForArray(int elementSqlTypeCode) {
+						return SqlTypes.JSON_ARRAY;
 					}
 				}
 		);
diff --git a/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayAggEmulation.java b/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayAggEmulation.java
index 194624b5882d..d0999e7a3892 100644
--- a/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayAggEmulation.java
+++ b/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayAggEmulation.java
@@ -73,7 +73,7 @@ public void render(
 					"Oracle array_agg emulation requires a basic plural return type, but resolved return type was: " + returnType
 			);
 		}
-		final boolean returnJson = pluralType.getJdbcType().getDefaultSqlTypeCode() == SqlTypes.JSON;
+		final boolean returnJson = pluralType.getJdbcType().getDefaultSqlTypeCode() == SqlTypes.JSON_ARRAY;
 		if ( returnJson ) {
 			sqlAppender.append( "json_arrayagg(" );
 		}
diff --git a/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayToStringFunction.java b/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayToStringFunction.java
index 60dca992af13..426ede516f4b 100644
--- a/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayToStringFunction.java
+++ b/hibernate-core/src/main/java/org/hibernate/dialect/function/array/OracleArrayToStringFunction.java
@@ -6,13 +6,22 @@
 
 import java.util.List;
 
+import org.hibernate.metamodel.mapping.JdbcMappingContainer;
 import org.hibernate.metamodel.model.domain.ReturnableType;
+import org.hibernate.query.sqm.function.SelfRenderingOrderedSetAggregateFunctionSqlAstExpression;
+import org.hibernate.sql.ast.Clause;
 import org.hibernate.sql.ast.SqlAstTranslator;
 import org.hibernate.sql.ast.spi.SqlAppender;
 import org.hibernate.sql.ast.tree.SqlAstNode;
 import org.hibernate.sql.ast.tree.expression.Expression;
+import org.hibernate.sql.ast.tree.expression.FunctionExpression;
+import org.hibernate.sql.ast.tree.predicate.Predicate;
+import org.hibernate.sql.ast.tree.select.SortSpecification;
+import org.hibernate.type.SqlTypes;
 import org.hibernate.type.spi.TypeConfiguration;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 /**
  * Oracle array_to_string function.
  */
@@ -28,22 +37,89 @@ public void render(
 			List<? extends SqlAstNode> sqlAstArguments,
 			ReturnableType<?> returnType,
 			SqlAstTranslator<?> walker) {
-		final String arrayTypeName = DdlTypeHelper.getTypeName(
-				( (Expression) sqlAstArguments.get( 0 ) ).getExpressionType(),
-				walker.getSessionFactory().getTypeConfiguration()
-		);
-		sqlAppender.append( arrayTypeName );
-		sqlAppender.append( "_to_string(" );
-		sqlAstArguments.get( 0 ).accept( walker );
-		sqlAppender.append( ',' );
-		sqlAstArguments.get( 1 ).accept( walker );
-		if ( sqlAstArguments.size() > 2 ) {
+		final Expression arrayExpression = (Expression) sqlAstArguments.get( 0 );
+		final JdbcMappingContainer expressionType = (arrayExpression).getExpressionType();
+		if ( arrayExpression instanceof SelfRenderingOrderedSetAggregateFunctionSqlAstExpression
+				&& ArrayAggFunction.FUNCTION_NAME.equals( ( (FunctionExpression) arrayExpression ).getFunctionName() ) ) {
+			final SelfRenderingOrderedSetAggregateFunctionSqlAstExpression functionExpression
+					= (SelfRenderingOrderedSetAggregateFunctionSqlAstExpression) arrayExpression;
+			// When the array argument is an aggregate expression, we access its contents directly
+			final Expression arrayElementExpression = (Expression) functionExpression.getArguments().get( 0 );
+			final @Nullable Expression defaultExpression =
+					sqlAstArguments.size() > 2 ? (Expression) sqlAstArguments.get( 2 ) : null;
+			final List<SortSpecification> withinGroup = functionExpression.getWithinGroup();
+			final Predicate filter = functionExpression.getFilter();
+
+			sqlAppender.append( "listagg(" );
+			if ( filter != null ) {
+				sqlAppender.appendSql( "case when " );
+				walker.getCurrentClauseStack().push( Clause.WHERE );
+				filter.accept( walker );
+				walker.getCurrentClauseStack().pop();
+				sqlAppender.appendSql( " then " );
+			}
+			if ( defaultExpression != null ) {
+				sqlAppender.append( "coalesce(" );
+			}
+			arrayElementExpression.accept( walker );
+			if ( defaultExpression != null ) {
+				sqlAppender.append( ',' );
+				defaultExpression.accept( walker );
+				sqlAppender.append( ')' );
+			}
+			if ( filter != null ) {
+				sqlAppender.appendSql( " else null end" );
+			}
 			sqlAppender.append( ',' );
-			sqlAstArguments.get( 2 ).accept( walker );
+			sqlAstArguments.get( 1 ).accept( walker );
+			sqlAppender.appendSql( ')' );
+
+			if ( withinGroup != null && !withinGroup.isEmpty() ) {
+				walker.getCurrentClauseStack().push( Clause.WITHIN_GROUP );
+				sqlAppender.appendSql( " within group (order by " );
+				withinGroup.get( 0 ).accept( walker );
+				for ( int i = 1; i < withinGroup.size(); i++ ) {
+					sqlAppender.appendSql( ',' );
+					withinGroup.get( i ).accept( walker );
+				}
+				sqlAppender.appendSql( ')' );
+				walker.getCurrentClauseStack().pop();
+			}
+		}
+		else if ( expressionType.getSingleJdbcMapping().getJdbcType().getDefaultSqlTypeCode() ==  SqlTypes.JSON_ARRAY ) {
+			sqlAppender.append( "(select listagg(" );
+			if ( sqlAstArguments.size() > 2 ) {
+				sqlAppender.append( "coalesce(t.v," );
+				sqlAstArguments.get( 2 ).accept( walker );
+				sqlAppender.append( ")," );
+			}
+			else {
+				sqlAppender.append( "t.v," );
+			}
+
+			sqlAstArguments.get( 1 ).accept( walker );
+			sqlAppender.append( ") from json_table(" );
+			sqlAstArguments.get( 0 ).accept( walker );
+			sqlAppender.append( ",'$[*]' columns (v path '$')) t)" );
 		}
 		else {
-			sqlAppender.append( ",null" );
+			final String arrayTypeName = DdlTypeHelper.getTypeName(
+					expressionType,
+					walker.getSessionFactory().getTypeConfiguration()
+			);
+			sqlAppender.append( arrayTypeName );
+			sqlAppender.append( "_to_string(" );
+			sqlAstArguments.get( 0 ).accept( walker );
+			sqlAppender.append( ',' );
+			sqlAstArguments.get( 1 ).accept( walker );
+			if ( sqlAstArguments.size() > 2 ) {
+				sqlAppender.append( ',' );
+				sqlAstArguments.get( 2 ).accept( walker );
+			}
+			else {
+				sqlAppender.append( ",null" );
+			}
+			sqlAppender.append( ')' );
 		}
-		sqlAppender.append( ')' );
 	}
 }
diff --git a/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayAggregateTest.java b/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayAggregateTest.java
index b82f31039630..e255416ba04f 100644
--- a/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayAggregateTest.java
+++ b/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayAggregateTest.java
@@ -30,6 +30,7 @@
 import org.hibernate.testing.orm.junit.BootstrapServiceRegistry;
 import org.hibernate.testing.orm.junit.DialectFeatureChecks;
 import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
 import org.hibernate.testing.orm.junit.RequiresDialectFeature;
 import org.hibernate.testing.orm.junit.SessionFactory;
 import org.hibernate.testing.orm.junit.SessionFactoryScope;
@@ -158,4 +159,15 @@ public void testNodeBuilder(SessionFactoryScope scope) {
 		} );
 	}
 
+	@Test
+	@Jira("https://hibernate.atlassian.net/browse/HHH-19666")
+	public void testNonExistingArrayType(SessionFactoryScope scope) {
+		scope.inSession( em -> {
+			List<Integer[]> results = em.createQuery( "select array_agg(e.id) within group (order by e.id) from EntityOfBasics e", Integer[].class )
+					.getResultList();
+			assertEquals( 1, results.size() );
+			assertArrayEquals( new Integer[]{ 1, 2, 3 }, results.get( 0 ) );
+		} );
+	}
+
 }
diff --git a/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayToStringWithArrayAggregateTest.java b/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayToStringWithArrayAggregateTest.java
index e314615efc51..d1f42210c1e9 100644
--- a/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayToStringWithArrayAggregateTest.java
+++ b/hibernate-core/src/test/java/org/hibernate/orm/test/function/array/ArrayToStringWithArrayAggregateTest.java
@@ -7,6 +7,7 @@
 import jakarta.persistence.Entity;
 import jakarta.persistence.Id;
 import jakarta.persistence.Tuple;
+import org.hibernate.dialect.OracleDialect;
 import org.hibernate.query.criteria.JpaCriteriaQuery;
 import org.hibernate.query.criteria.JpaCteCriteria;
 import org.hibernate.query.criteria.JpaRoot;
@@ -18,6 +19,7 @@
 import org.hibernate.testing.orm.junit.RequiresDialectFeature;
 import org.hibernate.testing.orm.junit.SessionFactory;
 import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.hibernate.testing.orm.junit.SkipForDialect;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -72,6 +74,7 @@ public void test(SessionFactoryScope scope) {
 	}
 
 	@Test
+	@SkipForDialect(dialectClass = OracleDialect.class, majorVersion = 21, reason = "Oracle bug in version 21")
 	public void testWithCte(SessionFactoryScope scope) {
 		scope.inSession( em -> {
 			final NodeBuilder cb = (NodeBuilder) em.getCriteriaBuilder();