diff --git a/internal/cmd/gtrace/main.go b/internal/cmd/gtrace/main.go
index 84a16add4..41e96b24a 100644
--- a/internal/cmd/gtrace/main.go
+++ b/internal/cmd/gtrace/main.go
@@ -20,7 +20,7 @@ import (
 	"github.com/ydb-platform/ydb-go-sdk/v3/internal/xerrors"
 )
 
-//nolint:gocyclo
+//nolint:gocyclo,funlen
 func main() {
 	var (
 		// Reports whether we were called from go:generate.
diff --git a/internal/cmd/gtrace/writer.go b/internal/cmd/gtrace/writer.go
index 16e30ad2c..463f544f8 100644
--- a/internal/cmd/gtrace/writer.go
+++ b/internal/cmd/gtrace/writer.go
@@ -372,6 +372,7 @@ func (w *Writer) composeHook(hook Hook, t1, t2, dst string) {
 	w.line(`}`)
 }
 
+//nolint:funlen
 func (w *Writer) composeHookCall(fn *Func, h1, h2 string) {
 	w.newScope(func() {
 		w.capture(h1, h2)
diff --git a/internal/credentials/oauth2.go b/internal/credentials/oauth2.go
index f49826127..1fc5da7d3 100644
--- a/internal/credentials/oauth2.go
+++ b/internal/credentials/oauth2.go
@@ -349,62 +349,89 @@ func (provider *oauth2TokenExchange) getRequestParams() (string, error) {
 }
 
 func (provider *oauth2TokenExchange) processTokenExchangeResponse(result *http.Response, now time.Time) error {
-	var (
-		data []byte
-		err  error
-	)
-	if result.Body != nil {
-		data, err = io.ReadAll(result.Body)
-		if err != nil {
-			return xerrors.WithStackTrace(err)
-		}
-	} else {
-		data = make([]byte, 0)
+	data, err := readResponseBody(result)
+	if err != nil {
+		return err
 	}
 
 	if result.StatusCode != http.StatusOK {
-		description := result.Status
+		return provider.handleErrorResponse(result.Status, data)
+	}
 
-		//nolint:tagliatelle
-		type errorResponse struct {
-			ErrorName        string `json:"error"`
-			ErrorDescription string `json:"error_description"`
-			ErrorURI         string `json:"error_uri"`
-		}
-		var parsedErrorResponse errorResponse
-		if err := json.Unmarshal(data, &parsedErrorResponse); err != nil {
-			description += ", could not parse response: " + err.Error()
+	parsedResponse, err := parseTokenResponse(data)
+	if err != nil {
+		return err
+	}
 
-			return xerrors.WithStackTrace(fmt.Errorf("%w: %s", errCouldNotExchangeToken, description))
-		}
+	if err := validateTokenResponse(parsedResponse, provider); err != nil {
+		return err
+	}
 
-		if parsedErrorResponse.ErrorName != "" {
-			description += ", error: " + parsedErrorResponse.ErrorName
-		}
+	provider.updateToken(parsedResponse, now)
 
-		if parsedErrorResponse.ErrorDescription != "" {
-			description += fmt.Sprintf(", description: %q", parsedErrorResponse.ErrorDescription)
-		}
+	return nil
+}
 
-		if parsedErrorResponse.ErrorURI != "" {
-			description += ", error_uri: " + parsedErrorResponse.ErrorURI
+func readResponseBody(result *http.Response) ([]byte, error) {
+	if result.Body != nil {
+		data, err := io.ReadAll(result.Body)
+		if err != nil {
+			return nil, xerrors.WithStackTrace(err)
 		}
 
-		return xerrors.WithStackTrace(fmt.Errorf("%w: %s", errCouldNotExchangeToken, description))
+		return data, nil
 	}
 
+	return make([]byte, 0), nil
+}
+
+func (provider *oauth2TokenExchange) handleErrorResponse(status string, data []byte) error {
+	description := status
+
 	//nolint:tagliatelle
-	type response struct {
-		AccessToken string `json:"access_token"`
-		TokenType   string `json:"token_type"`
-		ExpiresIn   int64  `json:"expires_in"`
-		Scope       string `json:"scope"`
+	type errorResponse struct {
+		ErrorName        string `json:"error"`
+		ErrorDescription string `json:"error_description"`
+		ErrorURI         string `json:"error_uri"`
+	}
+	var parsedErrorResponse errorResponse
+	if err := json.Unmarshal(data, &parsedErrorResponse); err != nil {
+		description += ", could not parse response: " + err.Error()
+
+		return xerrors.WithStackTrace(fmt.Errorf("%w: %s", errCouldNotExchangeToken, description))
 	}
-	var parsedResponse response
+
+	if parsedErrorResponse.ErrorName != "" {
+		description += ", error: " + parsedErrorResponse.ErrorName
+	}
+	if parsedErrorResponse.ErrorDescription != "" {
+		description += fmt.Sprintf(", description: %q", parsedErrorResponse.ErrorDescription)
+	}
+	if parsedErrorResponse.ErrorURI != "" {
+		description += ", error_uri: " + parsedErrorResponse.ErrorURI
+	}
+
+	return xerrors.WithStackTrace(fmt.Errorf("%w: %s", errCouldNotExchangeToken, description))
+}
+
+//nolint:tagliatelle
+type tokenResponse struct {
+	AccessToken string `json:"access_token"`
+	TokenType   string `json:"token_type"`
+	ExpiresIn   int64  `json:"expires_in"`
+	Scope       string `json:"scope"`
+}
+
+func parseTokenResponse(data []byte) (*tokenResponse, error) {
+	var parsedResponse tokenResponse
 	if err := json.Unmarshal(data, &parsedResponse); err != nil {
-		return xerrors.WithStackTrace(fmt.Errorf("%w: %w", errCouldNotParseResponse, err))
+		return nil, xerrors.WithStackTrace(fmt.Errorf("%w: %w", errCouldNotParseResponse, err))
 	}
 
+	return &parsedResponse, nil
+}
+
+func validateTokenResponse(parsedResponse *tokenResponse, provider *oauth2TokenExchange) error {
 	if !strings.EqualFold(parsedResponse.TokenType, "bearer") {
 		return xerrors.WithStackTrace(
 			fmt.Errorf("%w: %q", errUnsupportedTokenType, parsedResponse.TokenType))
@@ -423,18 +450,17 @@ func (provider *oauth2TokenExchange) processTokenExchangeResponse(result *http.R
 		}
 	}
 
+	return nil
+}
+
+func (provider *oauth2TokenExchange) updateToken(parsedResponse *tokenResponse, now time.Time) {
 	provider.receivedToken = "Bearer " + parsedResponse.AccessToken
 
-	// Expire time
-	expireDelta := time.Duration(parsedResponse.ExpiresIn)
-	expireDelta *= time.Second
+	expireDelta := time.Duration(parsedResponse.ExpiresIn) * time.Second
 	provider.receivedTokenExpireTime = now.Add(expireDelta)
 
-	updateDelta := time.Duration(parsedResponse.ExpiresIn / updateTimeDivider)
-	updateDelta *= time.Second
+	updateDelta := time.Duration(parsedResponse.ExpiresIn/updateTimeDivider) * time.Second
 	provider.updateTokenTime = now.Add(updateDelta)
-
-	return nil
 }
 
 func (provider *oauth2TokenExchange) exchangeToken(ctx context.Context, now time.Time) error {
diff --git a/internal/credentials/static.go b/internal/credentials/static.go
index 7d9437dfb..5c6328992 100644
--- a/internal/credentials/static.go
+++ b/internal/credentials/static.go
@@ -87,9 +87,7 @@ func (c *Static) Token(ctx context.Context) (token string, err error) {
 			fmt.Errorf("dial failed: %w", err),
 		)
 	}
-	defer func() {
-		_ = cc.Close()
-	}()
+	defer cc.Close()
 
 	client := Ydb_Auth_V1.NewAuthServiceClient(cc)
 
diff --git a/internal/decimal/decimal.go b/internal/decimal/decimal.go
index 2795592e8..5926562f5 100644
--- a/internal/decimal/decimal.go
+++ b/internal/decimal/decimal.go
@@ -224,6 +224,8 @@ func handleRemainingDigits(s string, v *big.Int, precision uint32) (*big.Int, er
 
 // Format returns the string representation of x with the given precision and
 // scale.
+//
+//nolint:funlen
 func Format(x *big.Int, precision, scale uint32) string {
 	// Check for special values and nil pointer upfront.
 	if x == nil {
diff --git a/internal/value/nullable.go b/internal/value/nullable.go
index 894b1ca8c..8a532d9e1 100644
--- a/internal/value/nullable.go
+++ b/internal/value/nullable.go
@@ -299,7 +299,7 @@ func NullableDyNumberValue(v *string) Value {
 // Nullable makes optional value from nullable type
 // Warning: type interface will be replaced in the future with typed parameters pattern from go1.18
 //
-//nolint:gocyclo
+//nolint:gocyclo, funlen
 func Nullable(t types.Type, v interface{}) Value {
 	switch t {
 	case types.Bool:
diff --git a/internal/value/value.go b/internal/value/value.go
index 5e0b2a29f..095f56174 100644
--- a/internal/value/value.go
+++ b/internal/value/value.go
@@ -78,6 +78,7 @@ func nullValueFromYDB(x *Ydb.Value, t types.Type) (_ Value, ok bool) {
 	}
 }
 
+//nolint:funlen
 func primitiveValueFromYDB(t types.Primitive, v *Ydb.Value) (Value, error) {
 	switch t {
 	case types.Bool:
@@ -167,6 +168,7 @@ func primitiveValueFromYDB(t types.Primitive, v *Ydb.Value) (Value, error) {
 	}
 }
 
+//nolint:funlen
 func fromYDB(t *Ydb.Type, v *Ydb.Value) (Value, error) {
 	tt := types.TypeFromYDB(t)
 
@@ -2307,6 +2309,7 @@ func YSONValue(v []byte) ysonValue {
 	return v
 }
 
+//nolint:funlen
 func zeroPrimitiveValue(t types.Primitive) Value {
 	switch t {
 	case types.Bool:
diff --git a/retry/sql.go b/retry/sql.go
index 23706971e..5bf974351 100644
--- a/retry/sql.go
+++ b/retry/sql.go
@@ -130,6 +130,8 @@ func WithTxOptions(txOptions *sql.TxOptions) txOptionsOption {
 }
 
 // DoTx is a retryer of database/sql transactions with fallbacks on errors
+//
+//nolint:funlen
 func DoTx(ctx context.Context, db *sql.DB, op func(context.Context, *sql.Tx) error, opts ...doTxOption) error {
 	var (
 		options = doTxOptions{