diff --git a/content_scripts/notify.js b/content_scripts/notify.js
index ee0d96d72..1a8f56b99 100644
--- a/content_scripts/notify.js
+++ b/content_scripts/notify.js
@@ -13,12 +13,14 @@
  You should have received a copy of the GNU General Public License along with
  TALER; see the file COPYING.  If not, If not, see <http://www.gnu.org/licenses/>
  */
-/// <reference path="../lib/decl/chrome/chrome.d.ts" />
-"use strict";
 /**
  * Script that is injected into (all!) pages to allow them
  * to interact with the GNU Taler wallet via DOM Events.
+ *
+ * @author Florian Dold
  */
+/// <reference path="../lib/decl/chrome/chrome.d.ts" />
+"use strict";
 // Make sure we don't pollute the namespace too much.
 var TalerNotify;
 (function (TalerNotify) {
diff --git a/lib/wallet/db.ts b/lib/wallet/db.ts
index 2503468d5..9374aa447 100644
--- a/lib/wallet/db.ts
+++ b/lib/wallet/db.ts
@@ -25,7 +25,7 @@
  */
 
 const DB_NAME = "taler";
-const DB_VERSION = 1;
+const DB_VERSION = 5;
 
 /**
  * Return a promise that resolves
@@ -45,7 +45,8 @@ export function openTalerDb(): Promise<IDBDatabase> {
       console.log("DB: upgrade needed: oldVersion = " + e.oldVersion);
       switch (e.oldVersion) {
         case 0: // DB does not exist yet
-          const exchanges = db.createObjectStore("exchanges", {keyPath: "baseUrl"});
+          const exchanges = db.createObjectStore("exchanges",
+                                                 {keyPath: "baseUrl"});
           exchanges.createIndex("pubKey", "masterPublicKey");
           db.createObjectStore("reserves", {keyPath: "reserve_pub"});
           db.createObjectStore("denoms", {keyPath: "denomPub"});
@@ -68,6 +69,15 @@ export function openTalerDb(): Promise<IDBDatabase> {
                                                });
           history.createIndex("timestamp", "timestamp");
           break;
+        default:
+          if (e.oldVersion != DB_VERSION) {
+            window.alert("Incompatible wallet dababase version, please reset" +
+                         " db.");
+            chrome.browserAction.setBadgeText({text: "R!"});
+            chrome.browserAction.setBadgeBackgroundColor({color: "#F00"});
+            throw Error("incompatible DB");
+          }
+          break;
       }
     };
   });
diff --git a/lib/wallet/wallet.ts b/lib/wallet/wallet.ts
index 94ac8ee8a..3764edfbc 100644
--- a/lib/wallet/wallet.ts
+++ b/lib/wallet/wallet.ts
@@ -912,7 +912,10 @@ export class Wallet {
 
     return Query(this.db)
       .iter("coins")
-      .reduce(collectBalances, {});
+      .reduce(collectBalances, {})
+      .then(byCurrency => {
+        return {balances: byCurrency};
+      });
   }
 
 
@@ -922,7 +925,7 @@ export class Wallet {
   getHistory(): Promise<any[]> {
     function collect(x, acc) {
       acc.push(x);
-      return acc;
+      return {history: acc};
     }
 
     return Query(this.db)
diff --git a/lib/wallet/wxMessaging.ts b/lib/wallet/wxMessaging.ts
index a6b3f9d1b..d49a80efb 100644
--- a/lib/wallet/wxMessaging.ts
+++ b/lib/wallet/wxMessaging.ts
@@ -47,9 +47,11 @@ function makeHandlers(db: IDBDatabase,
       return exportDb(db);
     },
     ["reset"]: function(detail) {
-      let tx = db.transaction(db.objectStoreNames, 'readwrite');
-      for (let i = 0; i < db.objectStoreNames.length; i++) {
-        tx.objectStore(db.objectStoreNames[i]).clear();
+      if (db) {
+        let tx = db.transaction(db.objectStoreNames, 'readwrite');
+        for (let i = 0; i < db.objectStoreNames.length; i++) {
+          tx.objectStore(db.objectStoreNames[i]).clear();
+        }
       }
       deleteDb();
 
diff --git a/popup/popup.tsx b/popup/popup.tsx
index 2cd753e4f..be33f870a 100644
--- a/popup/popup.tsx
+++ b/popup/popup.tsx
@@ -95,6 +95,7 @@ namespace WalletBalance {
 
   class Controller {
     myWallet;
+    gotError = false;
 
     constructor() {
       this.updateBalance();
@@ -104,9 +105,16 @@ namespace WalletBalance {
 
     updateBalance() {
       m.startComputation();
-      chrome.runtime.sendMessage({type: "balances"}, (wallet) => {
-        console.log("got wallet", wallet);
-        this.myWallet = wallet;
+      chrome.runtime.sendMessage({type: "balances"}, (resp) => {
+        if (resp.error) {
+          this.gotError = true;
+          console.error("could not retrieve balances", resp);
+          m.endComputation();
+          return;
+        }
+        this.gotError = false;
+        console.log("got wallet", resp);
+        this.myWallet = resp.balances;
         m.endComputation();
       });
     }
@@ -114,6 +122,9 @@ namespace WalletBalance {
 
   export function view(ctrl: Controller) {
     let wallet = ctrl.myWallet;
+    if (ctrl.gotError) {
+      return i18n`Error: could not retrieve balance information.`;
+    }
     if (!wallet) {
       throw Error("Could not retrieve wallet");
     }
@@ -200,6 +211,7 @@ namespace WalletHistory {
 
   class Controller {
     myHistory;
+    gotError = false;
 
     constructor() {
       this.update();
@@ -209,8 +221,15 @@ namespace WalletHistory {
     update() {
       m.startComputation();
       chrome.runtime.sendMessage({type: "get-history"}, (resp) => {
-        console.log("got history", history);
-        this.myHistory = resp;
+        if (resp.error) {
+          this.gotError = true;
+          console.error("could not retrieve history", resp);
+          m.endComputation();
+          return;
+        }
+        this.gotError = false;
+        console.log("got history", resp.history);
+        this.myHistory = resp.history;
         m.endComputation();
       });
     }
@@ -218,6 +237,9 @@ namespace WalletHistory {
 
   export function view(ctrl: Controller) {
     let history = ctrl.myHistory;
+    if (ctrl.gotError) {
+      return i18n`Error: could not retrieve event history`;
+    }
     if (!history) {
       throw Error("Could not retrieve history");
     }