diff --git a/.github/workflows/e2e.yml b/.github/workflows/e2e.yml
index 71e57e11..2e458a80 100644
--- a/.github/workflows/e2e.yml
+++ b/.github/workflows/e2e.yml
@@ -37,7 +37,7 @@ jobs:
       # resolution options, using npm release or a gh ref:
       #
       # option #1, set the version of stellar-sdk based on a npm release version
-      SYSTEM_TEST_JS_STELLAR_SDK_NPM_VERSION: 11.1.0
+      SYSTEM_TEST_JS_STELLAR_SDK_NPM_VERSION: 11.3.0
       # option #2, set the version of stellar-sdk used as a ref to a gh repo if
       # a value is set on SYSTEM_TEST_JS_STELLAR_SDK_GH_REPO, it takes
       # precedence over any SYSTEM_TEST_JS_STELLAR_SDK_NPM_VERSION
diff --git a/cmd/soroban-rpc/internal/jsonrpc.go b/cmd/soroban-rpc/internal/jsonrpc.go
index b0ceb372..59d83420 100644
--- a/cmd/soroban-rpc/internal/jsonrpc.go
+++ b/cmd/soroban-rpc/internal/jsonrpc.go
@@ -208,7 +208,7 @@ func NewJSONRPCHandler(cfg *config.Config, params HandlerParams) Handler {
 		},
 		{
 			methodName:           "simulateTransaction",
-			underlyingHandler:    methods.NewSimulateTransactionHandler(params.Logger, params.LedgerEntryReader, params.LedgerReader, params.PreflightGetter),
+			underlyingHandler:    methods.NewSimulateTransactionHandler(params.Logger, params.LedgerEntryReader, params.LedgerReader, params.Daemon, params.PreflightGetter),
 			longName:             "simulate_transaction",
 			queueLimit:           cfg.RequestBacklogSimulateTransactionQueueLimit,
 			requestDurationLimit: cfg.MaxSimulateTransactionExecutionDuration,
diff --git a/cmd/soroban-rpc/internal/methods/get_events.go b/cmd/soroban-rpc/internal/methods/get_events.go
index dda0fa06..8b4a9439 100644
--- a/cmd/soroban-rpc/internal/methods/get_events.go
+++ b/cmd/soroban-rpc/internal/methods/get_events.go
@@ -8,7 +8,6 @@ import (
 	"time"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 
 	"github.com/stellar/go/strkey"
 	"github.com/stellar/go/support/errors"
@@ -429,7 +428,7 @@ func NewGetEventsHandler(eventsStore *events.MemoryStore, maxLimit, defaultLimit
 		maxLimit:     maxLimit,
 		defaultLimit: defaultLimit,
 	}
-	return handler.New(func(ctx context.Context, request GetEventsRequest) (GetEventsResponse, error) {
+	return NewHandler(func(ctx context.Context, request GetEventsRequest) (GetEventsResponse, error) {
 		return eventsHandler.getEvents(request)
 	})
 }
diff --git a/cmd/soroban-rpc/internal/methods/get_latest_ledger.go b/cmd/soroban-rpc/internal/methods/get_latest_ledger.go
index 2f933304..3617e70d 100644
--- a/cmd/soroban-rpc/internal/methods/get_latest_ledger.go
+++ b/cmd/soroban-rpc/internal/methods/get_latest_ledger.go
@@ -4,7 +4,6 @@ import (
 	"context"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 
 	"github.com/stellar/soroban-rpc/cmd/soroban-rpc/internal/db"
 )
@@ -20,7 +19,7 @@ type GetLatestLedgerResponse struct {
 
 // NewGetLatestLedgerHandler returns a JSON RPC handler to retrieve the latest ledger entry from Stellar core.
 func NewGetLatestLedgerHandler(ledgerEntryReader db.LedgerEntryReader, ledgerReader db.LedgerReader) jrpc2.Handler {
-	return handler.New(func(ctx context.Context) (GetLatestLedgerResponse, error) {
+	return NewHandler(func(ctx context.Context) (GetLatestLedgerResponse, error) {
 		tx, err := ledgerEntryReader.NewTx(ctx)
 		if err != nil {
 			return GetLatestLedgerResponse{}, &jrpc2.Error{
diff --git a/cmd/soroban-rpc/internal/methods/get_ledger_entries.go b/cmd/soroban-rpc/internal/methods/get_ledger_entries.go
index e9e58868..c3f2b617 100644
--- a/cmd/soroban-rpc/internal/methods/get_ledger_entries.go
+++ b/cmd/soroban-rpc/internal/methods/get_ledger_entries.go
@@ -5,7 +5,6 @@ import (
 	"fmt"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 	"github.com/stellar/go/support/log"
 	"github.com/stellar/go/xdr"
 
@@ -40,7 +39,7 @@ const getLedgerEntriesMaxKeys = 200
 
 // NewGetLedgerEntriesHandler returns a JSON RPC handler to retrieve the specified ledger entries from Stellar Core.
 func NewGetLedgerEntriesHandler(logger *log.Entry, ledgerEntryReader db.LedgerEntryReader) jrpc2.Handler {
-	return handler.New(func(ctx context.Context, request GetLedgerEntriesRequest) (GetLedgerEntriesResponse, error) {
+	return NewHandler(func(ctx context.Context, request GetLedgerEntriesRequest) (GetLedgerEntriesResponse, error) {
 		if len(request.Keys) > getLedgerEntriesMaxKeys {
 			return GetLedgerEntriesResponse{}, &jrpc2.Error{
 				Code:    jrpc2.InvalidParams,
diff --git a/cmd/soroban-rpc/internal/methods/get_ledger_entry.go b/cmd/soroban-rpc/internal/methods/get_ledger_entry.go
index e457a3b1..910d2155 100644
--- a/cmd/soroban-rpc/internal/methods/get_ledger_entry.go
+++ b/cmd/soroban-rpc/internal/methods/get_ledger_entry.go
@@ -5,8 +5,6 @@ import (
 	"fmt"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
-
 	"github.com/stellar/go/support/log"
 	"github.com/stellar/go/xdr"
 
@@ -33,7 +31,7 @@ type GetLedgerEntryResponse struct {
 // Deprecated. use NewGetLedgerEntriesHandler instead.
 // TODO(https://github.com/stellar/soroban-tools/issues/374) remove after getLedgerEntries is deployed.
 func NewGetLedgerEntryHandler(logger *log.Entry, ledgerEntryReader db.LedgerEntryReader) jrpc2.Handler {
-	return handler.New(func(ctx context.Context, request GetLedgerEntryRequest) (GetLedgerEntryResponse, error) {
+	return NewHandler(func(ctx context.Context, request GetLedgerEntryRequest) (GetLedgerEntryResponse, error) {
 		var key xdr.LedgerKey
 		if err := xdr.SafeUnmarshalBase64(request.Key, &key); err != nil {
 			logger.WithError(err).WithField("request", request).
diff --git a/cmd/soroban-rpc/internal/methods/get_network.go b/cmd/soroban-rpc/internal/methods/get_network.go
index 5c990c41..f706e7c6 100644
--- a/cmd/soroban-rpc/internal/methods/get_network.go
+++ b/cmd/soroban-rpc/internal/methods/get_network.go
@@ -4,7 +4,6 @@ import (
 	"context"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 
 	"github.com/stellar/soroban-rpc/cmd/soroban-rpc/internal/daemon/interfaces"
 )
@@ -20,7 +19,7 @@ type GetNetworkResponse struct {
 // NewGetNetworkHandler returns a json rpc handler to for the getNetwork method
 func NewGetNetworkHandler(daemon interfaces.Daemon, networkPassphrase, friendbotURL string) jrpc2.Handler {
 	coreClient := daemon.CoreClient()
-	return handler.New(func(ctx context.Context, request GetNetworkRequest) (GetNetworkResponse, error) {
+	return NewHandler(func(ctx context.Context, request GetNetworkRequest) (GetNetworkResponse, error) {
 		info, err := coreClient.Info(ctx)
 		if err != nil {
 			return GetNetworkResponse{}, (&jrpc2.Error{
diff --git a/cmd/soroban-rpc/internal/methods/get_transaction.go b/cmd/soroban-rpc/internal/methods/get_transaction.go
index 1e6ef610..166cb152 100644
--- a/cmd/soroban-rpc/internal/methods/get_transaction.go
+++ b/cmd/soroban-rpc/internal/methods/get_transaction.go
@@ -7,7 +7,6 @@ import (
 	"fmt"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 	"github.com/stellar/go/xdr"
 
 	"github.com/stellar/soroban-rpc/cmd/soroban-rpc/internal/ledgerbucketwindow"
@@ -121,7 +120,7 @@ func GetTransaction(getter transactionGetter, request GetTransactionRequest) (Ge
 
 // NewGetTransactionHandler returns a get transaction json rpc handler
 func NewGetTransactionHandler(getter transactionGetter) jrpc2.Handler {
-	return handler.New(func(ctx context.Context, request GetTransactionRequest) (GetTransactionResponse, error) {
+	return NewHandler(func(ctx context.Context, request GetTransactionRequest) (GetTransactionResponse, error) {
 		return GetTransaction(getter, request)
 	})
 }
diff --git a/cmd/soroban-rpc/internal/methods/handler.go b/cmd/soroban-rpc/internal/methods/handler.go
new file mode 100644
index 00000000..2dc4d99b
--- /dev/null
+++ b/cmd/soroban-rpc/internal/methods/handler.go
@@ -0,0 +1,17 @@
+package methods
+
+import (
+	"github.com/creachadair/jrpc2"
+	"github.com/creachadair/jrpc2/handler"
+)
+
+func NewHandler(fn any) jrpc2.Handler {
+	fi, err := handler.Check(fn)
+	if err != nil {
+		panic(err)
+	}
+	// explicitly disable array arguments since otherwise we cannot add
+	// new method arguments without breaking backwards compatibility with clients
+	fi.AllowArray(false)
+	return fi.Wrap()
+}
diff --git a/cmd/soroban-rpc/internal/methods/handler_test.go b/cmd/soroban-rpc/internal/methods/handler_test.go
new file mode 100644
index 00000000..564f7f51
--- /dev/null
+++ b/cmd/soroban-rpc/internal/methods/handler_test.go
@@ -0,0 +1,60 @@
+package methods
+
+import (
+	"context"
+	"testing"
+
+	"github.com/creachadair/jrpc2"
+	"github.com/creachadair/jrpc2/handler"
+	"github.com/stretchr/testify/assert"
+)
+
+type Request struct {
+	Parameter string `json:"parameter"`
+}
+
+func TestNewHandlerNoArrayParameters(t *testing.T) {
+	callCount := 0
+	f := func(ctx context.Context, request Request) error {
+		callCount++
+		assert.Equal(t, "bar", request.Parameter)
+		return nil
+	}
+	objectRequest := `{
+"jsonrpc": "2.0",
+"id": 1,
+"method": "foo",
+"params": { "parameter": "bar" }
+}`
+	requests, err := jrpc2.ParseRequests([]byte(objectRequest))
+	assert.NoError(t, err)
+	assert.Len(t, requests, 1)
+	finalObjectRequest := requests[0].ToRequest()
+
+	// object parameters should work with our handlers
+	customHandler := NewHandler(f)
+	_, err = customHandler(context.Background(), finalObjectRequest)
+	assert.NoError(t, err)
+	assert.Equal(t, 1, callCount)
+
+	arrayRequest := `{
+"jsonrpc": "2.0",
+"id": 1,
+"method": "foo",
+"params": ["bar"]
+}`
+	requests, err = jrpc2.ParseRequests([]byte(arrayRequest))
+	assert.NoError(t, err)
+	assert.Len(t, requests, 1)
+	finalArrayRequest := requests[0].ToRequest()
+
+	// Array requests should work with the normal handler, but not with our handlers
+	stdHandler := handler.New(f)
+	_, err = stdHandler(context.Background(), finalArrayRequest)
+	assert.NoError(t, err)
+	assert.Equal(t, 2, callCount)
+
+	_, err = customHandler(context.Background(), finalArrayRequest)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "invalid parameters")
+}
diff --git a/cmd/soroban-rpc/internal/methods/health.go b/cmd/soroban-rpc/internal/methods/health.go
index b8f684af..f9b1c50e 100644
--- a/cmd/soroban-rpc/internal/methods/health.go
+++ b/cmd/soroban-rpc/internal/methods/health.go
@@ -6,7 +6,6 @@ import (
 	"time"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 
 	"github.com/stellar/soroban-rpc/cmd/soroban-rpc/internal/ledgerbucketwindow"
 )
@@ -24,7 +23,7 @@ type LedgerRangeGetter interface {
 
 // NewHealthCheck returns a health check json rpc handler
 func NewHealthCheck(retentionWindow uint32, ledgerRangeGetter LedgerRangeGetter, maxHealthyLedgerLatency time.Duration) jrpc2.Handler {
-	return handler.New(func(ctx context.Context) (HealthCheckResult, error) {
+	return NewHandler(func(ctx context.Context) (HealthCheckResult, error) {
 		ledgerRange := ledgerRangeGetter.GetLedgerRange()
 		if ledgerRange.LastLedger.Sequence < 1 {
 			return HealthCheckResult{}, jrpc2.Error{
diff --git a/cmd/soroban-rpc/internal/methods/send_transaction.go b/cmd/soroban-rpc/internal/methods/send_transaction.go
index 215e2998..82d014d1 100644
--- a/cmd/soroban-rpc/internal/methods/send_transaction.go
+++ b/cmd/soroban-rpc/internal/methods/send_transaction.go
@@ -5,7 +5,6 @@ import (
 	"encoding/hex"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 	"github.com/stellar/go/network"
 	proto "github.com/stellar/go/protocols/stellarcore"
 	"github.com/stellar/go/support/log"
@@ -47,7 +46,7 @@ type SendTransactionRequest struct {
 // NewSendTransactionHandler returns a submit transaction json rpc handler
 func NewSendTransactionHandler(daemon interfaces.Daemon, logger *log.Entry, ledgerRangeGetter LedgerRangeGetter, passphrase string) jrpc2.Handler {
 	submitter := daemon.CoreClient()
-	return handler.New(func(ctx context.Context, request SendTransactionRequest) (SendTransactionResponse, error) {
+	return NewHandler(func(ctx context.Context, request SendTransactionRequest) (SendTransactionResponse, error) {
 		var envelope xdr.TransactionEnvelope
 		err := xdr.SafeUnmarshalBase64(request.Transaction, &envelope)
 		if err != nil {
diff --git a/cmd/soroban-rpc/internal/methods/simulate_transaction.go b/cmd/soroban-rpc/internal/methods/simulate_transaction.go
index 6ad3c63b..9ad98d80 100644
--- a/cmd/soroban-rpc/internal/methods/simulate_transaction.go
+++ b/cmd/soroban-rpc/internal/methods/simulate_transaction.go
@@ -9,10 +9,10 @@ import (
 	"strings"
 
 	"github.com/creachadair/jrpc2"
-	"github.com/creachadair/jrpc2/handler"
 	"github.com/stellar/go/support/log"
 	"github.com/stellar/go/xdr"
 
+	"github.com/stellar/soroban-rpc/cmd/soroban-rpc/internal/daemon/interfaces"
 	"github.com/stellar/soroban-rpc/cmd/soroban-rpc/internal/db"
 	"github.com/stellar/soroban-rpc/cmd/soroban-rpc/internal/preflight"
 )
@@ -157,9 +157,9 @@ type PreflightGetter interface {
 }
 
 // NewSimulateTransactionHandler returns a json rpc handler to run preflight simulations
-func NewSimulateTransactionHandler(logger *log.Entry, ledgerEntryReader db.LedgerEntryReader, ledgerReader db.LedgerReader, getter PreflightGetter) jrpc2.Handler {
+func NewSimulateTransactionHandler(logger *log.Entry, ledgerEntryReader db.LedgerEntryReader, ledgerReader db.LedgerReader, daemon interfaces.Daemon, getter PreflightGetter) jrpc2.Handler {
 
-	return handler.New(func(ctx context.Context, request SimulateTransactionRequest) SimulateTransactionResponse {
+	return NewHandler(func(ctx context.Context, request SimulateTransactionRequest) SimulateTransactionResponse {
 		var txEnvelope xdr.TransactionEnvelope
 		if err := xdr.SafeUnmarshalBase64(request.Transaction, &txEnvelope); err != nil {
 			logger.WithError(err).WithField("request", request).
@@ -213,7 +213,7 @@ func NewSimulateTransactionHandler(logger *log.Entry, ledgerEntryReader db.Ledge
 				Error: err.Error(),
 			}
 		}
-		bucketListSize, err := getBucketListSize(ctx, ledgerReader, latestLedger)
+		bucketListSize, protocolVersion, err := getBucketListSizeAndProtocolVersion(ctx, ledgerReader, latestLedger)
 		if err != nil {
 			return SimulateTransactionResponse{
 				Error: err.Error(),
@@ -231,6 +231,7 @@ func NewSimulateTransactionHandler(logger *log.Entry, ledgerEntryReader db.Ledge
 			OperationBody:     op.Body,
 			Footprint:         footprint,
 			ResourceConfig:    resource_config,
+			ProtocolVersion:   protocolVersion,
 		}
 		result, err := getter.GetPreflight(ctx, params)
 		if err != nil {
@@ -285,17 +286,17 @@ func base64EncodeSlice(in [][]byte) []string {
 	return result
 }
 
-func getBucketListSize(ctx context.Context, ledgerReader db.LedgerReader, latestLedger uint32) (uint64, error) {
+func getBucketListSizeAndProtocolVersion(ctx context.Context, ledgerReader db.LedgerReader, latestLedger uint32) (uint64, uint32, error) {
 	// obtain bucket size
 	var closeMeta, ok, err = ledgerReader.GetLedger(ctx, latestLedger)
 	if err != nil {
-		return 0, err
+		return 0, 0, err
 	}
 	if !ok {
-		return 0, fmt.Errorf("missing meta for latest ledger (%d)", latestLedger)
+		return 0, 0, fmt.Errorf("missing meta for latest ledger (%d)", latestLedger)
 	}
 	if closeMeta.V != 1 {
-		return 0, fmt.Errorf("latest ledger (%d) meta has unexpected verion (%d)", latestLedger, closeMeta.V)
+		return 0, 0, fmt.Errorf("latest ledger (%d) meta has unexpected verion (%d)", latestLedger, closeMeta.V)
 	}
-	return uint64(closeMeta.V1.TotalByteSizeOfBucketList), nil
+	return uint64(closeMeta.V1.TotalByteSizeOfBucketList), uint32(closeMeta.V1.LedgerHeader.Header.LedgerVersion), nil
 }
diff --git a/cmd/soroban-rpc/internal/preflight/pool.go b/cmd/soroban-rpc/internal/preflight/pool.go
index 4eeddb53..3ea704d8 100644
--- a/cmd/soroban-rpc/internal/preflight/pool.go
+++ b/cmd/soroban-rpc/internal/preflight/pool.go
@@ -156,6 +156,7 @@ func (pwp *PreflightWorkerPool) GetPreflight(ctx context.Context, params Preflig
 		Footprint:         params.Footprint,
 		ResourceConfig:    params.ResourceConfig,
 		EnableDebug:       pwp.enableDebug,
+		ProtocolVersion:   params.ProtocolVersion,
 	}
 	resultC := make(chan workerResult)
 	select {
diff --git a/cmd/soroban-rpc/internal/preflight/preflight.go b/cmd/soroban-rpc/internal/preflight/preflight.go
index de3c7f4e..37ddcc9b 100644
--- a/cmd/soroban-rpc/internal/preflight/preflight.go
+++ b/cmd/soroban-rpc/internal/preflight/preflight.go
@@ -91,6 +91,7 @@ type PreflightGetterParameters struct {
 	OperationBody     xdr.OperationBody
 	Footprint         xdr.LedgerFootprint
 	ResourceConfig    ResourceConfig
+	ProtocolVersion   uint32
 }
 
 type PreflightParameters struct {
@@ -103,6 +104,7 @@ type PreflightParameters struct {
 	BucketListSize    uint64
 	ResourceConfig    ResourceConfig
 	EnableDebug       bool
+	ProtocolVersion   uint32
 }
 
 type XDRDiff struct {
@@ -174,7 +176,7 @@ func getLedgerInfo(params PreflightParameters) (C.ledger_info_t, error) {
 	li := C.ledger_info_t{
 		network_passphrase: C.CString(params.NetworkPassphrase),
 		sequence_number:    C.uint32_t(simulationLedgerSeq),
-		protocol_version:   21,
+		protocol_version:   C.uint32_t(params.ProtocolVersion),
 		timestamp:          C.uint64_t(time.Now().Unix()),
 		// Current base reserve is 0.5XLM (in stroops)
 		base_reserve:     5_000_000,
diff --git a/cmd/soroban-rpc/internal/preflight/preflight_test.go b/cmd/soroban-rpc/internal/preflight/preflight_test.go
index 401912e4..1d4515b0 100644
--- a/cmd/soroban-rpc/internal/preflight/preflight_test.go
+++ b/cmd/soroban-rpc/internal/preflight/preflight_test.go
@@ -359,6 +359,7 @@ func getPreflightParameters(t testing.TB, dbConfig *preflightParametersDBConfig)
 		NetworkPassphrase: "foo",
 		LedgerEntryReadTx: ledgerEntryReadTx,
 		BucketListSize:    200,
+		ProtocolVersion:   20,
 	}
 	return params
 }