diff --git a/types/office-js-preview/index.d.ts b/types/office-js-preview/index.d.ts
index ecbc77fd20..b5ea7dd6db 100644
--- a/types/office-js-preview/index.d.ts
+++ b/types/office-js-preview/index.d.ts
@@ -11255,6 +11255,8 @@ declare namespace Office {
      * The user defines {@link Office.MasterCategories | categories in a master list} on their mailbox.
      * They can then apply one or more categories to an item.
      *
+     * **Important**: In Outlook on the web, you can't use the API to manage categories on a message in Read mode.
+     *
      * [Api set: Mailbox 1.8]
      *
      * @remarks
@@ -14103,6 +14105,8 @@ declare namespace Office {
         /**
          * Gets an object that provides methods for managing the item's categories.
          *
+         * **Important**: In Outlook on the web, you can't use the API to manage categories on a message in Read mode.
+         *
          * [Api set: Mailbox 1.8]
          *
          * @remarks
diff --git a/types/office-js/index.d.ts b/types/office-js/index.d.ts
index df453d9dcb..50e904a990 100644
--- a/types/office-js/index.d.ts
+++ b/types/office-js/index.d.ts
@@ -11068,6 +11068,8 @@ declare namespace Office {
      * The user defines {@link Office.MasterCategories | categories in a master list} on their mailbox.
      * They can then apply one or more categories to an item.
      *
+     * **Important**: In Outlook on the web, you can't use the API to manage categories on a message in Read mode.
+     *
      * [Api set: Mailbox 1.8]
      *
      * @remarks
@@ -13864,6 +13866,8 @@ declare namespace Office {
         /**
          * Gets an object that provides methods for managing the item's categories.
          *
+         * **Important**: In Outlook on the web, you can't use the API to manage categories on a message in Read mode.
+         *
          * [Api set: Mailbox 1.8]
          *
          * @remarks