diff --git a/ydb/core/external_sources/object_storage.cpp b/ydb/core/external_sources/object_storage.cpp
index ecf72445a11c..1cca2267a091 100644
--- a/ydb/core/external_sources/object_storage.cpp
+++ b/ydb/core/external_sources/object_storage.cpp
@@ -150,6 +150,7 @@ struct TObjectStorageExternalSource : public IExternalSource {
         }
         const bool hasPartitioning = objectStorage.projection_size() || objectStorage.partitioned_by_size();
         issues.AddIssues(ValidateFormatSetting(objectStorage.format(), objectStorage.format_setting(), location, hasPartitioning));
+        issues.AddIssues(ValidateSchema(schema));
         issues.AddIssues(ValidateJsonListFormat(objectStorage.format(), schema, objectStorage.partitioned_by()));
         issues.AddIssues(ValidateRawFormat(objectStorage.format(), schema, objectStorage.partitioned_by()));
         if (hasPartitioning) {
@@ -268,6 +269,22 @@ struct TObjectStorageExternalSource : public IExternalSource {
         return issues;
     }
 
+    template<typename TScheme>
+    static NYql::TIssues ValidateSchema(const TScheme& schema) {
+        NYql::TIssues issues;
+        for (const auto& column: schema.column()) {
+            const auto type = column.type();
+            if (type.has_optional_type() && type.optional_type().item().has_optional_type()) {
+                issues.AddIssue(MakeErrorIssue(
+                    Ydb::StatusIds::BAD_REQUEST,
+                    TStringBuilder{} << "Double optional types are not supported (you have '" 
+                        << column.name() << " " << NYdb::TType(column.type()).ToString() << "' field)"));
+            }
+        }
+
+        return issues;
+    }
+
     template<typename TScheme>
     static NYql::TIssues ValidateJsonListFormat(const TString& format, const TScheme& schema, const google::protobuf::RepeatedPtrField<TString>& partitionedBy) {
         NYql::TIssues issues;
diff --git a/ydb/core/external_sources/object_storage_ut.cpp b/ydb/core/external_sources/object_storage_ut.cpp
index d5bc4a655d3f..129ad8febd7d 100644
--- a/ydb/core/external_sources/object_storage_ut.cpp
+++ b/ydb/core/external_sources/object_storage_ut.cpp
@@ -55,6 +55,15 @@ Y_UNIT_TEST_SUITE(ObjectStorageTest) {
         UNIT_ASSERT_EXCEPTION_CONTAINS(source->Pack(schema, general), NExternalSource::TExternalSourceException, "Date, Timestamp and Interval types are not allowed in json_list format");
     }
 
+    Y_UNIT_TEST(FailedOptionalTypeValidation) {
+        auto source = NExternalSource::CreateObjectStorageExternalSource({}, nullptr, 1000, nullptr, false, false);
+        NKikimrExternalSources::TSchema schema;
+        NKikimrExternalSources::TGeneral general;
+        auto newColumn = schema.add_column();
+        newColumn->mutable_type()->mutable_optional_type()->mutable_item()->mutable_optional_type()->mutable_item()->set_type_id(Ydb::Type::INT32);
+        UNIT_ASSERT_EXCEPTION_CONTAINS(source->Pack(schema, general), NExternalSource::TExternalSourceException, "Double optional types are not supported");
+    }
+
     Y_UNIT_TEST(WildcardsValidation) {
         auto source = NExternalSource::CreateObjectStorageExternalSource({}, nullptr, 1000, nullptr, false, false);
         NKikimrExternalSources::TSchema schema;
diff --git a/ydb/library/yql/providers/s3/common/util.cpp b/ydb/library/yql/providers/s3/common/util.cpp
index 594040188745..074b116cc8c2 100644
--- a/ydb/library/yql/providers/s3/common/util.cpp
+++ b/ydb/library/yql/providers/s3/common/util.cpp
@@ -48,4 +48,20 @@ TString UrlEscapeRet(const TStringBuf from) {
     return to;
 }
 
+bool ValidateS3ReadWriteSchema(const TStructExprType* schemaStructRowType, TExprContext& ctx) {
+    for (const TItemExprType* item : schemaStructRowType->GetItems()) {
+        const TTypeAnnotationNode* rowType = item->GetItemType();
+        if (rowType->GetKind() == ETypeAnnotationKind::Optional) {
+            rowType = rowType->Cast<TOptionalExprType>()->GetItemType();
+        }
+
+        if (rowType->GetKind() == ETypeAnnotationKind::Optional) {
+            ctx.AddError(TIssue(TStringBuilder() << "Double optional types are not supported (you have '"
+                << item->GetName() << " " << FormatType(item->GetItemType()) << "' field)"));
+            return false;
+        }
+    }
+    return true;
+}
+
 }
diff --git a/ydb/library/yql/providers/s3/common/util.h b/ydb/library/yql/providers/s3/common/util.h
index 8767742e31f5..d364e971078f 100644
--- a/ydb/library/yql/providers/s3/common/util.h
+++ b/ydb/library/yql/providers/s3/common/util.h
@@ -2,6 +2,7 @@
 
 #include <util/string/builder.h>
 #include <yql/essentials/public/issue/yql_issue.h>
+#include <yql/essentials/ast/yql_expr.h>
 
 namespace NYql::NS3Util {
 
@@ -12,4 +13,6 @@ TIssues AddParentIssue(const TStringBuilder& prefix, TIssues&& issues);
 // '#', '?'
 TString UrlEscapeRet(const TStringBuf from);
 
+bool ValidateS3ReadWriteSchema(const TStructExprType* schemaStructRowType, TExprContext& ctx);
+
 }
diff --git a/ydb/library/yql/providers/s3/common/ya.make b/ydb/library/yql/providers/s3/common/ya.make
index 4927e3b10d66..058d0ca92fd2 100644
--- a/ydb/library/yql/providers/s3/common/ya.make
+++ b/ydb/library/yql/providers/s3/common/ya.make
@@ -18,6 +18,7 @@ PEERDIR(
     ydb/library/yql/providers/s3/events
     yql/essentials/public/issue
     yql/essentials/public/issue/protos
+    yql/essentials/ast
 )
 
 IF (CLANG AND NOT WITH_VALGRIND)
diff --git a/ydb/library/yql/providers/s3/provider/yql_s3_datasink_type_ann.cpp b/ydb/library/yql/providers/s3/provider/yql_s3_datasink_type_ann.cpp
index ecda21b92813..350431400b7e 100644
--- a/ydb/library/yql/providers/s3/provider/yql_s3_datasink_type_ann.cpp
+++ b/ydb/library/yql/providers/s3/provider/yql_s3_datasink_type_ann.cpp
@@ -2,6 +2,7 @@
 
 #include <yql/essentials/core/expr_nodes/yql_expr_nodes.h>
 #include <yql/essentials/core/yql_opt_utils.h>
+#include <ydb/library/yql/providers/s3/common/util.h>
 #include <ydb/library/yql/providers/s3/expr_nodes/yql_s3_expr_nodes.h>
 
 #include <yql/essentials/providers/common/provider/yql_provider.h>
@@ -26,6 +27,7 @@ TExprNode::TListType GetPartitionKeys(const TExprNode::TPtr& partBy) {
 
     return {};
 }
+
 }
 
 namespace {
@@ -74,6 +76,10 @@ class TS3DataSinkTypeAnnotationTransformer : public TVisitorTransformerBase {
             return TStatus::Error;
         }
 
+        if (!NS3Util::ValidateS3ReadWriteSchema(sourceType->Cast<TStructExprType>(), ctx)) {
+            return TStatus::Error;
+        }
+
         auto target = input->Child(TS3WriteObject::idx_Target);
         if (!TS3Target::Match(target)) {
             ctx.AddError(TIssue(ctx.GetPosition(target->Pos()), "Expected S3 target."));
diff --git a/ydb/library/yql/providers/s3/provider/yql_s3_datasource_type_ann.cpp b/ydb/library/yql/providers/s3/provider/yql_s3_datasource_type_ann.cpp
index 6bfb9b641345..a94de088fc65 100644
--- a/ydb/library/yql/providers/s3/provider/yql_s3_datasource_type_ann.cpp
+++ b/ydb/library/yql/providers/s3/provider/yql_s3_datasource_type_ann.cpp
@@ -1,6 +1,7 @@
 #include "yql_s3_provider_impl.h"
 
 #include <yql/essentials/core/expr_nodes/yql_expr_nodes.h>
+#include <ydb/library/yql/providers/s3/common/util.h>
 #include <ydb/library/yql/providers/s3/expr_nodes/yql_s3_expr_nodes.h>
 #include <ydb/library/yql/providers/s3/path_generator/yql_s3_path_generator.h>
 #include <ydb/library/yql/providers/s3/range_helpers/path_list_reader.h>
@@ -491,6 +492,10 @@ class TS3DataSourceTypeAnnotationTransformer : public TVisitorTransformerBase {
             auto format = s3Object.Format().Ref().Content();
             const TStructExprType* structRowType = rowType->Cast<TStructExprType>();
 
+            if (!NS3Util::ValidateS3ReadWriteSchema(structRowType, ctx)) {
+                return TStatus::Error;
+            }
+
             THashSet<TStringBuf> columns;
             for (const TItemExprType* item : structRowType->GetItems()) {
                 columns.emplace(item->GetName());
diff --git a/ydb/tests/fq/s3/test_s3_0.py b/ydb/tests/fq/s3/test_s3_0.py
index e5ea35c0abc4..1e527706db24 100644
--- a/ydb/tests/fq/s3/test_s3_0.py
+++ b/ydb/tests/fq/s3/test_s3_0.py
@@ -1114,3 +1114,56 @@ def wait_checkpoints(require_query_is_on=False):
 
         client.abort_query(query_id)
         client.wait_query(query_id)
+
+    @yq_v2
+    @pytest.mark.parametrize("client", [{"folder_id": "my_folder"}], indirect=True)
+    def test_double_optional_types_validation(self, kikimr, s3, client, unique_prefix):
+        resource = boto3.resource(
+            "s3", endpoint_url=s3.s3_url, aws_access_key_id="key", aws_secret_access_key="secret_key"
+        )
+
+        bucket = resource.Bucket("fbucket")
+        bucket.create(ACL='public-read')
+        bucket.objects.all().delete()
+
+        s3_client = boto3.client(
+            "s3", endpoint_url=s3.s3_url, aws_access_key_id="key", aws_secret_access_key="secret_key"
+        )
+
+        fruits = '''Fruit,Price,Weight
+Banana,3,100
+Apple,2,22
+Pear,15,33'''
+        s3_client.put_object(Body=fruits, Bucket='fbucket', Key='fruits.csv', ContentType='text/plain')
+
+        kikimr.control_plane.wait_bootstrap(1)
+        storage_connection_name = unique_prefix + "fruitbucket"
+        client.create_storage_connection(storage_connection_name, "fbucket")
+
+        sql = f'''
+            SELECT *
+            FROM `{storage_connection_name}`.`fruits.csv`
+            WITH (format='csv_with_names', SCHEMA (
+                Name Int32??,
+            ));
+            '''
+
+        query_id = client.create_query("simple", sql, type=fq.QueryContent.QueryType.ANALYTICS).result.query_id
+        client.wait_query_status(query_id, fq.QueryMeta.FAILED)
+        issues = str(client.describe_query(query_id).result.query.issue)
+
+        assert "Double optional types are not supported" in issues, "Incorrect issues: " + issues
+
+        sql = f'''
+            INSERT INTO `{storage_connection_name}`.`insert/`
+            WITH
+            (
+                FORMAT="csv_with_names"
+            )
+            SELECT CAST(42 AS Int32??) as Weight;'''
+
+        query_id = client.create_query("simple", sql, type=fq.QueryContent.QueryType.ANALYTICS).result.query_id
+        client.wait_query_status(query_id, fq.QueryMeta.FAILED)
+        issues = str(client.describe_query(query_id).result.query.issue)
+
+        assert "Double optional types are not supported" in issues, "Incorrect issues: " + issues