diff --git a/internal/server/usermanager/api.yaml b/internal/server/usermanager/api.yaml
index d49875d..30c12cc 100644
--- a/internal/server/usermanager/api.yaml
+++ b/internal/server/usermanager/api.yaml
@@ -149,4 +149,4 @@ externalDocs:
 host: 127.0.0.1:8080
 basePath: /
 schemes:
-  - http
\ No newline at end of file
+  - http
diff --git a/internal/server/usermanager/localmanager.go b/internal/server/usermanager/localmanager.go
index ed466cb..63552bb 100644
--- a/internal/server/usermanager/localmanager.go
+++ b/internal/server/usermanager/localmanager.go
@@ -222,6 +222,14 @@ func (manager *localManager) WriteUserInfo(u UserInfo) (err error) {
 		if err != nil {
 			return err
 		}
+		k, v := bucket.Cursor().First()
+		// Registration required full UserInfo
+		if k == nil && v == nil {
+			if u.SessionsCap == nil || u.UpRate == nil || u.DownRate == nil ||
+				u.UpCredit == nil || u.DownCredit == nil || u.ExpiryTime == nil {
+				return ErrInvalidUserInfo
+			}
+		}
 		if u.SessionsCap != nil {
 			if err = bucket.Put([]byte("SessionsCap"), i32ToB(*u.SessionsCap)); err != nil {
 				return err
diff --git a/internal/server/usermanager/localmanager_test.go b/internal/server/usermanager/localmanager_test.go
index 6b28e8f..01d1b99 100644
--- a/internal/server/usermanager/localmanager_test.go
+++ b/internal/server/usermanager/localmanager_test.go
@@ -41,10 +41,16 @@ func TestLocalManager_WriteUserInfo(t *testing.T) {
 	mgr, cleaner := makeManager(t)
 	defer cleaner()
 
-	err := mgr.WriteUserInfo(mockUserInfo)
-	if err != nil {
-		t.Error(err)
-	}
+	/* New user with partial UserInfo */
+	err := mgr.WriteUserInfo(UserInfo{
+		UID:         mockUID,
+		SessionsCap: JustInt32(*mockUserInfo.SessionsCap + 1),
+	})
+	assert.Error(t, err, ErrInvalidUserInfo)
+
+	/* New user with full UserInfo */
+	err = mgr.WriteUserInfo(mockUserInfo)
+	assert.NoError(t, err)
 
 	got, err := mgr.GetUserInfo(mockUID)
 	assert.NoError(t, err)
diff --git a/internal/server/usermanager/usermanager.go b/internal/server/usermanager/usermanager.go
index bb5456e..1055c04 100644
--- a/internal/server/usermanager/usermanager.go
+++ b/internal/server/usermanager/usermanager.go
@@ -52,6 +52,7 @@ var ErrMangerIsVoid = errors.New("cannot perform operation with user manager as
 var ErrNoUpCredit = errors.New("No upload credit left")
 var ErrNoDownCredit = errors.New("No download credit left")
 var ErrUserExpired = errors.New("User has expired")
+var ErrInvalidUserInfo = errors.New("Invalid user info")
 
 type UserManager interface {
 	AuthenticateUser([]byte) (int64, int64, error)