diff --git a/v5/client.go b/v5/client.go
index 19e669d..150b133 100644
--- a/v5/client.go
+++ b/v5/client.go
@@ -66,6 +66,10 @@ func (c *Client) GetRequest(urlWithParameters string, versioned ...bool) ([]byte
 		return res, 0, err
 	}
 
+	if resp.StatusCode >= http.StatusBadRequest && resp.StatusCode < http.StatusInternalServerError {
+		return res, resp.StatusCode, NewAPIError(res)
+	}
+
 	if c.Debug {
 		log.Printf("API Response: %s", res)
 	}
@@ -129,6 +133,10 @@ func (c *Client) PostRequest(uri string, postData interface{}, contType ...strin
 		return res, 0, err
 	}
 
+	if resp.StatusCode >= http.StatusBadRequest && resp.StatusCode < http.StatusInternalServerError {
+		return res, resp.StatusCode, NewAPIError(res)
+	}
+
 	if c.Debug {
 		log.Printf("API Response: %s", res)
 	}
diff --git a/v5/error.go b/v5/error.go
index 52964a9..0d8fdf3 100644
--- a/v5/error.go
+++ b/v5/error.go
@@ -1,11 +1,6 @@
 package v5
 
-import (
-	"encoding/json"
-	"strconv"
-)
-
-const ArrowHTML = 60
+import "encoding/json"
 
 // APIErrorsList struct.
 type APIErrorsList map[string]string
@@ -24,8 +19,8 @@ func (e *APIError) Error() string {
 func NewAPIError(dataResponse []byte) error {
 	a := &APIError{}
 
-	if dataResponse[0] == ArrowHTML {
-		a.ErrorMsg = "405 Not Allowed"
+	if dataResponse[0] == '<' {
+		a.ErrorMsg = "Account does not exist."
 		return a
 	}
 
@@ -35,21 +30,3 @@ func NewAPIError(dataResponse []byte) error {
 
 	return a
 }
-
-// ErrorsHandler returns map.
-func ErrorsHandler(errs interface{}) map[string]string {
-	m := make(map[string]string)
-
-	switch e := errs.(type) {
-	case map[string]interface{}:
-		for idx, val := range e {
-			m[idx] = val.(string)
-		}
-	case []interface{}:
-		for idx, val := range e {
-			m[strconv.Itoa(idx)] = val.(string)
-		}
-	}
-
-	return m
-}
diff --git a/v5/error_test.go b/v5/error_test.go
index 1c0535f..27194f8 100644
--- a/v5/error_test.go
+++ b/v5/error_test.go
@@ -1,6 +1,7 @@
 package v5
 
 import (
+	"reflect"
 	"testing"
 
 	"golang.org/x/xerrors"
@@ -8,7 +9,7 @@ import (
 
 func TestFailure_ApiErrorsSlice(t *testing.T) {
 	b := []byte(`{"success": false, "errorMsg": "Failed to activate module", "errors": ["Your account has insufficient funds to activate integration module"]}`)
-	expected := map[string]string{
+	expected := APIErrorsList{
 		"0": "Your account has insufficient funds to activate integration module",
 	}
 
@@ -16,7 +17,7 @@ func TestFailure_ApiErrorsSlice(t *testing.T) {
 	e := NewAPIError(b)
 
 	if xerrors.As(e, &expEr) {
-		if eq := expEr.Errors["0"] == expected["0"]; eq != true {
+		if eq := reflect.DeepEqual(expEr.Errors, expected); eq != true {
 			t.Errorf("%+v", eq)
 		}
 	} else {
@@ -26,7 +27,7 @@ func TestFailure_ApiErrorsSlice(t *testing.T) {
 
 func TestFailure_ApiErrorsMap(t *testing.T) {
 	b := []byte(`{"success": false, "errorMsg": "Failed to activate module", "errors": {"id": "ID must be an integer"}}`)
-	expected := map[string]string{
+	expected := APIErrorsList{
 		"id": "ID must be an integer",
 	}
 
@@ -34,7 +35,7 @@ func TestFailure_ApiErrorsMap(t *testing.T) {
 	e := NewAPIError(b)
 
 	if xerrors.As(e, &expEr) {
-		if eq := expected["id"] == expEr.Errors["id"]; eq != true {
+		if eq := reflect.DeepEqual(expEr.Errors, expected); eq != true {
 			t.Errorf("%+v", eq)
 		}
 	} else {
diff --git a/v5/marshaling.go b/v5/marshaling.go
index f58383a..34f762d 100644
--- a/v5/marshaling.go
+++ b/v5/marshaling.go
@@ -2,6 +2,8 @@ package v5
 
 import (
 	"encoding/json"
+	"fmt"
+	"strconv"
 )
 
 func (t Tag) MarshalJSON() ([]byte, error) {
@@ -13,6 +15,19 @@ func (a *APIErrorsList) UnmarshalJSON(data []byte) error {
 	if err := json.Unmarshal(data, &i); err != nil {
 		return err
 	}
-	*a = ErrorsHandler(i)
+
+	m := make(map[string]string)
+	switch e := i.(type) {
+	case map[string]interface{}:
+		for idx, val := range e {
+			m[idx] = fmt.Sprint(val)
+		}
+	case []interface{}:
+		for idx, val := range e {
+			m[strconv.Itoa(idx)] = fmt.Sprint(val)
+		}
+	}
+
+	*a = m
 	return nil
 }