diff --git a/src/matrix/storage/idb/schema.ts b/src/matrix/storage/idb/schema.ts
index 2aca60a2..2da4d65c 100644
--- a/src/matrix/storage/idb/schema.ts
+++ b/src/matrix/storage/idb/schema.ts
@@ -6,6 +6,8 @@ import {addRoomToIdentity} from "../../e2ee/DeviceTracker.js";
 import {SESSION_E2EE_KEY_PREFIX} from "../../e2ee/common.js";
 import {SummaryData} from "../../room/RoomSummary";
 import {RoomMemberStore, MemberData} from "./stores/RoomMemberStore";
+import {encodeKey as encodeBackupKey} from "./stores/SessionNeedingBackupStore";
+import {InboundGroupSessionStore, InboundGroupSessionEntry} from "./stores/InboundGroupSessionStore";
 import {RoomStateEntry} from "./stores/RoomStateStore";
 import {SessionStore} from "./stores/SessionStore";
 import {Store} from "./Store";
@@ -39,6 +41,21 @@ export const schema: MigrationFunc[] = [
 // TypeScript note: for now, do not bother introducing interfaces / alias
 // for old schemas. Just take them as `any`. 
 
+function createDatabaseNameHelper(db: IDBDatabase): ITransaction {
+    // the Store object gets passed in several things through the Transaction class (a wrapper around IDBTransaction),
+    // the only thing we should need here is the databaseName though, so we mock it out.
+    // ideally we should have an easier way to go from the idb primitive layer to the specific store classes where
+    // we implement logic, but for now we need this.
+    const databaseNameHelper: ITransaction = {
+        databaseName: db.name,
+        get idbFactory(): IDBFactory { throw new Error("unused");},
+        get IDBKeyRange(): typeof IDBKeyRange { throw new Error("unused");},
+        addWriteError() {},
+    };
+    return databaseNameHelper;
+}
+
+
 // how do we deal with schema updates vs existing data migration in a way that 
 //v1
 function createInitialStores(db: IDBDatabase): void {
@@ -223,17 +240,7 @@ async function changeSSSSKeyPrefix(db: IDBDatabase, txn: IDBTransaction) {
 // v13
 async function backupAndRestoreE2EEAccountToLocalStorage(db: IDBDatabase, txn: IDBTransaction, localStorage: IDOMStorage, log: ILogItem) {
     const session = txn.objectStore("session");
-    // the Store object gets passed in several things through the Transaction class (a wrapper around IDBTransaction),
-    // the only thing we should need here is the databaseName though, so we mock it out.
-    // ideally we should have an easier way to go from the idb primitive layer to the specific store classes where
-    // we implement logic, but for now we need this.
-    const databaseNameHelper: ITransaction = {
-        databaseName: db.name,
-        get idbFactory(): IDBFactory { throw new Error("unused");},
-        get IDBKeyRange(): typeof IDBKeyRange { throw new Error("unused");},
-        addWriteError() {},
-    };
-    const sessionStore = new SessionStore(new Store(session, databaseNameHelper), localStorage);
+    const sessionStore = new SessionStore(new Store(session, createDatabaseNameHelper(db)), localStorage);
     // if we already have an e2ee identity, write a backup to local storage.
     // further updates to e2ee keys in the session store will also write to local storage from 0.2.15 on,
     // but here we make sure a backup is immediately created after installing the update and we don't wait until
@@ -273,6 +280,25 @@ async function clearAllStores(db: IDBDatabase, txn: IDBTransaction) {
 }
 
 // v15 adds the sessionsNeedingBackup store, for key backup
-function createSessionsNeedingBackup(db: IDBDatabase): void {
-    db.createObjectStore("sessionsNeedingBackup", {keyPath: "key"});
+async function createSessionsNeedingBackup(db: IDBDatabase, txn: IDBTransaction, localStorage: IDOMStorage, log: ILogItem): Promise<void> {
+    const backupStore = db.createObjectStore("sessionsNeedingBackup", {keyPath: "key"});
+    const session = txn.objectStore("session");
+    const ssssKey = await reqAsPromise(session.get(`${SESSION_E2EE_KEY_PREFIX}ssssKey`) as IDBRequest<string>);
+    const keyBackupEnabled = !!ssssKey;
+    log.set("key backup", keyBackupEnabled);
+    if (keyBackupEnabled) {
+        let count = 0;
+        try {
+            const inboundGroupSessions = txn.objectStore("inboundGroupSessions");
+            await iterateCursor<InboundGroupSessionEntry>(inboundGroupSessions.openCursor(), session => {
+                backupStore.add({key: encodeBackupKey(session.roomId, session.senderKey, session.sessionId)});
+                count += 1;
+                return NOT_DONE;
+            });
+        } catch (err) {
+            txn.abort();
+            log.log("could not migrate operations").catch(err);
+        }
+        log.set("count", count);
+    }
 }
diff --git a/src/matrix/storage/idb/stores/SessionNeedingBackupStore.ts b/src/matrix/storage/idb/stores/SessionNeedingBackupStore.ts
index 71a383bb..327fce9a 100644
--- a/src/matrix/storage/idb/stores/SessionNeedingBackupStore.ts
+++ b/src/matrix/storage/idb/stores/SessionNeedingBackupStore.ts
@@ -26,7 +26,7 @@ type StorageEntry = {
     key: string
 };
 
-function encodeKey(roomId: string, senderKey: string, sessionId: string): string {
+export function encodeKey(roomId: string, senderKey: string, sessionId: string): string {
     return `${roomId}|${senderKey}|${sessionId}`;
 }