diff --git a/zou/app/services/tasks_service.py b/zou/app/services/tasks_service.py
index fb21633d0..ffb415bf8 100644
--- a/zou/app/services/tasks_service.py
+++ b/zou/app/services/tasks_service.py
@@ -1970,10 +1970,12 @@ def get_open_tasks(
             query_stats = query_stats.filter(Task.assignees.any(id=person_id))
 
     if start_date is not None:
+        start_date = func.cast(start_date, Task.start_date.type)
         query = query.filter(Task.start_date >= start_date)
         query_stats = query_stats.filter(Task.start_date >= start_date)
 
     if due_date is not None:
+        due_date = func.cast(due_date, Task.due_date.type)
         query = query.filter(Task.due_date <= due_date)
         query_stats = query_stats.filter(Task.due_date <= due_date)