diff --git a/pkg/models/project.go b/pkg/models/project.go
index 00e99630b1..066e9927c5 100644
--- a/pkg/models/project.go
+++ b/pkg/models/project.go
@@ -1083,6 +1083,46 @@ func (p *Project) Delete(s *xorm.Session, a web.Auth) (err error) {
 		}
 	}
 
+	// Delete related project entities
+	views, err := getViewsForProject(s, p.ID)
+	if err != nil {
+		return
+	}
+	viewIDs := []int64{}
+	for _, v := range views {
+		viewIDs = append(viewIDs, v.ID)
+	}
+
+	_, err = s.In("project_view_id", viewIDs).Delete(&Bucket{})
+	if err != nil {
+		return
+	}
+
+	_, err = s.In("id", viewIDs).Delete(&ProjectView{})
+	if err != nil {
+		return
+	}
+
+	err = removeFromFavorite(s, p.ID, a, FavoriteKindProject)
+	if err != nil {
+		return
+	}
+
+	_, err = s.Where("project_id = ?", p.ID).Delete(&LinkSharing{})
+	if err != nil {
+		return
+	}
+
+	_, err = s.Where("project_id = ?", p.ID).Delete(&ProjectUser{})
+	if err != nil {
+		return
+	}
+
+	_, err = s.Where("project_id = ?", p.ID).Delete(&TeamProject{})
+	if err != nil {
+		return
+	}
+
 	// Delete the project
 	_, err = s.ID(p.ID).Delete(&Project{})
 	if err != nil {
diff --git a/pkg/models/tasks.go b/pkg/models/tasks.go
index f6e69fe5a7..f08b71123c 100644
--- a/pkg/models/tasks.go
+++ b/pkg/models/tasks.go
@@ -1486,6 +1486,18 @@ func (t *Task) Delete(s *xorm.Session, a web.Auth) (err error) {
 		return
 	}
 
+	// Delete all positions
+	_, err = s.Where("task_id = ?", t.ID).Delete(&TaskPosition{})
+	if err != nil {
+		return
+	}
+
+	// Delete all bucket relations
+	_, err = s.Where("task_id = ?", t.ID).Delete(&TaskBucket{})
+	if err != nil {
+		return
+	}
+
 	// Actually delete the task
 	_, err = s.ID(t.ID).Delete(Task{})
 	if err != nil {