diff --git a/controllers/user.go b/controllers/user.go
index 0d4298da..fd786607 100644
--- a/controllers/user.go
+++ b/controllers/user.go
@@ -20,6 +20,7 @@ import (
 	"strings"
 
 	"github.com/beego/beego/utils/pagination"
+	"github.com/casdoor/casdoor/conf"
 	"github.com/casdoor/casdoor/object"
 	"github.com/casdoor/casdoor/util"
 )
@@ -293,6 +294,11 @@ func (c *ApiController) UpdateUser() {
 		return
 	}
 
+	isUsernameLowered := conf.GetConfigBool("isUsernameLowered")
+	if isUsernameLowered {
+		user.Name = strings.ToLower(user.Name)
+	}
+
 	isAdmin := c.IsAdmin()
 	if pass, err := object.CheckPermissionForUpdateUser(oldUser, &user, isAdmin, c.GetAcceptLanguage()); !pass {
 		c.ResponseError(err)
diff --git a/object/user.go b/object/user.go
index fbecd650..c9fb6396 100644
--- a/object/user.go
+++ b/object/user.go
@@ -877,6 +877,7 @@ func AddUsers(users []*User) (bool, error) {
 			}
 		}
 
+		user.Name = strings.TrimSpace(user.Name)
 		if isUsernameLowered {
 			user.Name = strings.ToLower(user.Name)
 		}
diff --git a/object/user_util.go b/object/user_util.go
index 1f55ba0a..addb691e 100644
--- a/object/user_util.go
+++ b/object/user_util.go
@@ -21,12 +21,11 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/casdoor/casdoor/conf"
 	"github.com/casdoor/casdoor/i18n"
-
-	jsoniter "github.com/json-iterator/go"
-
 	"github.com/casdoor/casdoor/idp"
 	"github.com/casdoor/casdoor/util"
+	jsoniter "github.com/json-iterator/go"
 	"github.com/xorm-io/core"
 )
 
@@ -57,6 +56,13 @@ func HasUserByField(organizationName string, field string, value string) bool {
 }
 
 func GetUserByFields(organization string, field string) (*User, error) {
+	isUsernameLowered := conf.GetConfigBool("isUsernameLowered")
+	if isUsernameLowered {
+		field = strings.ToLower(field)
+	}
+
+	field = strings.TrimSpace(field)
+
 	// check username
 	user, err := GetUserByField(organization, "name", field)
 	if err != nil || user != nil {