diff --git a/lang/ui.en.json b/lang/ui.en.json
index 86bcd4c85..0cd91d6a8 100644
--- a/lang/ui.en.json
+++ b/lang/ui.en.json
@@ -1447,6 +1447,14 @@
     "defaultMessage": "Stop recording",
     "description": "Button label to stop recording movement data while recording multiple samples"
   },
+  "storage-quota-exceeded-dialog-body": {
+    "defaultMessage": "You have reached your session's storage limit. Recent changes made on your session cannot be saved. Please reload the page to continue your session.",
+    "description": "Body of storage error dialog"
+  },
+  "storage-quota-exceeded-dialog-title": {
+    "defaultMessage": "Error auto-saving your session",
+    "description": "Title of storage error dialog"
+  },
   "support-request": {
     "defaultMessage": "Please consider <link>raising a support request</link>.",
     "description": "Support request link text"
diff --git a/src/components/DefaultPageLayout.tsx b/src/components/DefaultPageLayout.tsx
index a0ee4be52..28a39e5a6 100644
--- a/src/components/DefaultPageLayout.tsx
+++ b/src/components/DefaultPageLayout.tsx
@@ -24,7 +24,7 @@ import { useProject } from "../hooks/project-hooks";
 import { keyboardShortcuts, useShortcut } from "../keyboard-shortcut-hooks";
 import { PostImportDialogState } from "../model";
 import Tour from "../pages/Tour";
-import { useStore } from "../store";
+import { isStorageQuotaExceeded, useStore } from "../store";
 import { createHomePageUrl } from "../urls";
 import ActionBar from "./ActionBar/ActionBar";
 import ItemsRight from "./ActionBar/ActionBarItemsRight";
@@ -37,6 +37,7 @@ import NotCreateAiHexImportDialog from "./NotCreateAiHexImportDialog";
 import PreReleaseNotice from "./PreReleaseNotice";
 import ProjectDropTarget from "./ProjectDropTarget";
 import SaveDialogs from "./SaveDialogs";
+import StorageQuotaExceededErrorDialog from "./StorageQuotaExceededErrorDialog";
 
 interface DefaultPageLayoutProps {
   titleId?: string;
@@ -76,11 +77,14 @@ const DefaultPageLayout = ({
 
   const isFeedbackOpen = useStore((s) => s.isFeedbackFormOpen);
   const closeDialog = useStore((s) => s.closeDialog);
+  const isStorageQuotaExceededDialogOpen = isStorageQuotaExceeded();
 
   return (
     <>
       {/* Suppress dialogs to prevent overlapping dialogs */}
-      {!isNonConnectionDialogOpen && <ConnectionDialogs />}
+      {!isNonConnectionDialogOpen && !isStorageQuotaExceededDialogOpen && (
+        <ConnectionDialogs />
+      )}
       <Tour />
       <SaveDialogs />
       <NotCreateAiHexImportDialog
@@ -92,6 +96,9 @@ const DefaultPageLayout = ({
         isOpen={postImportDialogState === PostImportDialogState.Error}
       />
       <MakeCodeLoadErrorDialog />
+      <StorageQuotaExceededErrorDialog
+        isOpen={isStorageQuotaExceededDialogOpen}
+      />
       <FeedbackForm isOpen={isFeedbackOpen} onClose={closeDialog} />
       <ProjectDropTarget
         isEnabled={!isNonConnectionDialogOpen && !isConnectionDialogOpen}
diff --git a/src/components/StorageQuotaExceededErrorDialog.tsx b/src/components/StorageQuotaExceededErrorDialog.tsx
new file mode 100644
index 000000000..98abc0067
--- /dev/null
+++ b/src/components/StorageQuotaExceededErrorDialog.tsx
@@ -0,0 +1,64 @@
+/**
+ * (c) 2024, Micro:bit Educational Foundation and contributors
+ *
+ * SPDX-License-Identifier: MIT
+ */
+import {
+  Button,
+  HStack,
+  Modal,
+  ModalBody,
+  ModalContent,
+  ModalFooter,
+  ModalHeader,
+  ModalOverlay,
+  Text,
+  VStack,
+} from "@chakra-ui/react";
+import { FormattedMessage } from "react-intl";
+
+interface StorageQuotaExceededErrorDialogProps {
+  isOpen: boolean;
+}
+
+const StorageQuotaExceededErrorDialog = ({
+  isOpen,
+}: StorageQuotaExceededErrorDialogProps) => {
+  return (
+    <Modal
+      motionPreset="none"
+      isOpen={isOpen}
+      onClose={() => {}}
+      size="2xl"
+      isCentered
+    >
+      <ModalOverlay>
+        <ModalContent>
+          <ModalHeader>
+            <FormattedMessage id="storage-quota-exceeded-dialog-title" />
+          </ModalHeader>
+          <ModalBody>
+            <VStack textAlign="left" w="100%">
+              <Text w="100%">
+                <FormattedMessage id="storage-quota-exceeded-dialog-body" />
+              </Text>
+            </VStack>
+          </ModalBody>
+          <ModalFooter justifyContent="flex-end">
+            <HStack gap={5}>
+              <Button
+                onClick={() => window.location.reload()}
+                variant="primary"
+                size="lg"
+              >
+                <FormattedMessage id="reload-action" />
+              </Button>
+            </HStack>
+          </ModalFooter>
+        </ModalContent>
+      </ModalOverlay>
+    </Modal>
+  );
+};
+
+export default StorageQuotaExceededErrorDialog;
diff --git a/src/messages/ui.en.json b/src/messages/ui.en.json
index 1353ebc11..7e14df28a 100644
--- a/src/messages/ui.en.json
+++ b/src/messages/ui.en.json
@@ -2563,6 +2563,18 @@
       "value": "Stop recording"
     }
   ],
+  "storage-quota-exceeded-dialog-body": [
+    {
+      "type": 0,
+      "value": "You have reached your session's storage limit. Recent changes made on your session cannot be saved. Please reload the page to continue your session."
+    }
+  ],
+  "storage-quota-exceeded-dialog-title": [
+    {
+      "type": 0,
+      "value": "Error auto-saving your session"
+    }
+  ],
   "support-request": [
     {
       "type": 0,
diff --git a/src/store.ts b/src/store.ts
index c0bc7f84e..4567e7bf5 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -7,7 +7,7 @@
 import { Project } from "@microbit/makecode-embed/react";
 import * as tf from "@tensorflow/tfjs";
 import { create } from "zustand";
-import { devtools, persist } from "zustand/middleware";
+import { createJSONStorage, devtools, persist } from "zustand/middleware";
 import { useShallow } from "zustand/react/shallow";
 import { deployment } from "./deployment";
 import { flags } from "./flags";
@@ -1161,6 +1161,7 @@ const createMlStore = (logging: Logging) => {
         {
           version: 1,
           name: "ml",
+          storage: createJSONStorage(() => mlStorage),
           partialize: ({
             actions,
             project,
@@ -1211,6 +1212,26 @@ const createMlStore = (logging: Logging) => {
   );
 };
 
+const storageQuotaExceededKey = "QuotaExceededError";
+const mlStorage = {
+  getItem: localStorage.getItem,
+  setItem: (name: string, value: string) => {
+    try {
+      localStorage.setItem(name, value);
+    } catch (e) {
+      if ((e as Error).name === "QuotaExceededError") {
+        return localStorage.setItem(storageQuotaExceededKey, "1");
+      }
+      throw e;
+    }
+  },
+  removeItem: localStorage.removeItem,
+};
+
+export const isStorageQuotaExceeded = () => {
+  return localStorage.getItem(storageQuotaExceededKey) === "1";
+};
+
 export const useStore = createMlStore(deployment.logging);
 
 const getDataWindowFromActions = (actions: ActionData[]): DataWindow => {
@@ -1220,6 +1241,9 @@ const getDataWindowFromActions = (actions: ActionData[]): DataWindow => {
     : currentDataWindow;
 };
 
+// Reset storage quota exceeded state
+localStorage.setItem(storageQuotaExceededKey, "0");
+
 // Get data window from actions on app load.
 const { actions } = useStore.getState();
 useStore.setState(