diff --git a/web/src/components/DateTimeInput.tsx b/web/src/components/DateTimeInput.tsx
index a1901be05..6d0c126fc 100644
--- a/web/src/components/DateTimeInput.tsx
+++ b/web/src/components/DateTimeInput.tsx
@@ -2,7 +2,8 @@ import dayjs from "dayjs";
 import toast from "react-hot-toast";
 import { cn } from "@/lib/utils";
 
-const DATE_TIME_FORMAT = "M/D/YYYY, H:mm:ss";
+// must be compatible with JS Date.parse(), we use ISO 8601 (almost)
+const DATE_TIME_FORMAT = "YYYY-MM-DD HH:mm:ss";
 
 // convert Date to datetime string.
 const formatDate = (date: Date): string => {
@@ -23,12 +24,13 @@ const DateTimeInput: React.FC<Props> = ({ value, onChange }) => {
       onBlur={(e) => {
         const inputValue = e.target.value;
         if (inputValue) {
-          const date = dayjs(inputValue, DATE_TIME_FORMAT, true).toDate();
+          // note: inputValue must be compatible with JS Date.parse()
+          const date = dayjs(inputValue).toDate();
           // Check if the date is valid.
           if (!isNaN(date.getTime())) {
             onChange(date);
           } else {
-            toast.error("Invalid datetime format. Use format: 12/31/2023, 23:59:59");
+            toast.error("Invalid datetime format. Use format: 2023-12-31 23:59:59");
             e.target.value = formatDate(value);
           }
         }