diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6b3c3a81..2f0f4e19 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Change history for ui-calendar
 
+## 10.0.0 IN PROGRESS
+
+* *BREAKING* bump `react-intl` to `v6.4.4`. Refs UICAL-275
+
 ## [9.2.1] (https://github.com/folio-org/ui-calendar/tree/v9.2.1) (2023-03-16)
 
 * Fix placement of datepicker to prevent overflow. Refs UICAL-240
diff --git a/package.json b/package.json
index de140a9c..98f7d066 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@folio/calendar",
-  "version": "9.2.1",
+  "version": "10.0.0",
   "description": "Calendar settings",
   "repository": "folio-org/ui-calendar",
   "publishConfig": {
@@ -119,7 +119,7 @@
     "@folio/stripes-form": "^8.0.0",
     "@folio/stripes-smart-components": "^8.0.0",
     "@folio/stripes-testing": "^4.2.0",
-    "@formatjs/cli": "^4.2.21",
+    "@formatjs/cli": "^6.1.3",
     "@testing-library/jest-dom": "^5.16.5",
     "@testing-library/react": "^12.1.5",
     "@testing-library/react-hooks": "^8.0.1",
@@ -142,7 +142,7 @@
     "prettier": "^2.7.0",
     "react": "^17.0.2",
     "react-dom": "^17.0.2",
-    "react-intl": "^5.7.0",
+    "react-intl": "^6.4.4",
     "react-router-dom": "^5.2.0",
     "ts-jest": "^28.0.7",
     "typescript": "^4.7.4"
@@ -170,7 +170,7 @@
     "react": "^18.0.2",
     "react-dom": "^18.0.2",
     "react-final-form": "^6.5.9",
-    "react-intl": "^5.7.0",
+    "react-intl": "^6.4.4",
     "react-query": "^3.39.2",
     "react-router-dom": "^5.2.0"
   }
diff --git a/src/forms/CalendarForm/validation/validateExceptions.tsx b/src/forms/CalendarForm/validation/validateExceptions.tsx
index 74460d6f..1463c76f 100644
--- a/src/forms/CalendarForm/validation/validateExceptions.tsx
+++ b/src/forms/CalendarForm/validation/validateExceptions.tsx
@@ -77,7 +77,7 @@ export function validateExceptionOverlaps(
       i,
       startDate: dayjs
         .min(row.rows.map(({ startDate }) => dayjs(startDate)))
-        .startOf('day'),
+        ?.startOf('day') ?? dayjs(0),
       endDate: dayjs
         .max(row.rows.map(({ endDate }) => dayjs(endDate)))
         .endOf('day'),