diff --git a/src/core/pushnotifications/providers/pushnotifications.ts b/src/core/pushnotifications/providers/pushnotifications.ts
index 3a48abfc7..430d78000 100644
--- a/src/core/pushnotifications/providers/pushnotifications.ts
+++ b/src/core/pushnotifications/providers/pushnotifications.ts
@@ -200,6 +200,15 @@ export class CorePushNotificationsProvider {
         });
     }
 
+    /**
+     * Check whether the device can be registered in Moodle to receive push notifications.
+     *
+     * @return {boolean} Whether the device can be registered in Moodle.
+     */
+    canRegisterOnMoodle(): boolean {
+        return this.pushID && this.appProvider.isMobile();
+    }
+
     /**
      * Delete all badge records for a given site.
      *
@@ -658,7 +667,7 @@ export class CorePushNotificationsProvider {
     registerDeviceOnMoodle(siteId?: string, forceUnregister?: boolean): Promise<any> {
         this.logger.debug('Register device on Moodle.');
 
-        if (!this.pushID || !this.appProvider.isMobile()) {
+        if (!this.canRegisterOnMoodle()) {
             return Promise.reject(null);
         }
 
@@ -729,7 +738,7 @@ export class CorePushNotificationsProvider {
 
         if (siteId) {
             // Check if the site has a pending unregister.
-            promise = this.appDB.getRecords(CorePushNotificationsProvider.REGISTERED_DEVICES_TABLE, {siteid: siteId});
+            promise = this.appDB.getRecords(CorePushNotificationsProvider.PENDING_UNREGISTER_TABLE, {siteid: siteId});
         } else {
             // Get all pending unregisters.
             promise = this.appDB.getAllRecords(CorePushNotificationsProvider.PENDING_UNREGISTER_TABLE);
diff --git a/src/core/pushnotifications/providers/register-cron-handler.ts b/src/core/pushnotifications/providers/register-cron-handler.ts
index 0f04874b5..e2bc48b2c 100644
--- a/src/core/pushnotifications/providers/register-cron-handler.ts
+++ b/src/core/pushnotifications/providers/register-cron-handler.ts
@@ -42,7 +42,7 @@ export class CorePushNotificationsRegisterCronHandler implements CoreCronHandler
      * @return {Promise<any>}         Promise resolved when done, rejected if failure.
      */
     execute(siteId?: string): Promise<any> {
-        if (!siteId) {
+        if (!siteId || !this.pushNotificationsProvider.canRegisterOnMoodle()) {
             // It's not a specific site, don't do anything.
             return Promise.resolve();
         }
diff --git a/src/providers/utils/utils.ts b/src/providers/utils/utils.ts
index d3d09bf47..e1595c75b 100644
--- a/src/providers/utils/utils.ts
+++ b/src/providers/utils/utils.ts
@@ -742,11 +742,11 @@ export class CoreUtilsProvider {
      * @return {boolean} Whether the error was returned by the WebService.
      */
     isWebServiceError(error: any): boolean {
-        return typeof error.warningcode != 'undefined' || (typeof error.errorcode != 'undefined' &&
+        return error && (typeof error.warningcode != 'undefined' || (typeof error.errorcode != 'undefined' &&
                 error.errorcode != 'invalidtoken' && error.errorcode != 'userdeleted' && error.errorcode != 'upgraderunning' &&
                 error.errorcode != 'forcepasswordchangenotice' && error.errorcode != 'usernotfullysetup' &&
                 error.errorcode != 'sitepolicynotagreed' && error.errorcode != 'sitemaintenance' &&
-                (error.errorcode != 'accessexception' || error.message.indexOf('Invalid token - token expired') == -1));
+                (error.errorcode != 'accessexception' || error.message.indexOf('Invalid token - token expired') == -1)));
     }
 
     /**