Normally push notifications arrive quite quickly. As you send messages from OneSignal, we then send the requests to Google (FCM), Apple (APNS), Windows (WNS), and other messaging services. These push services then deliver the message to your subscribers depending on the platform.

When looking at a notification message report in your OneSignal dashboard, you can see how quickly it is sent to the push services.

If the subscription that was sent the push does not get it right away, it could be due to the following reasons.

Common reasons for push delays

Items to check if you are experiencing push delays. If you are still having issues, you can contact our support team with the OneSignal App ID, Subscription ID you tested, and the link to the notification message reports you sent.

Wifi & network connection

Some home and commercial wifi routers will cause the device's connection to the push services to close. The device later re-opens the connection and receives the delayed notifications. More discussion on this here.

Steps to check:

1. Connect to your mobile data (no wifi).
2. Open the app or browser on your device and have it in focus (you can see it).
3. Send your subscription a push notification.
   1. Depending on your mobile data network, you should get the push quickly.
4. Next, connect to your wifi.
5. Keep the app or browser open and in focus.
6. Send your subscription another push notification.
   1. This may be delayed depending on your wifi.
   2. If you get a delay, you may need to check your ports or security settings. Details on connecting to APNS and FCM here:
      1. FCM ports and your firewall
      2. If your Apple devices aren't getting Apple push notifications

Power saving, focus, and low power modes

Each platform has a name for when the device is either low on power or the user wants to save battery life. Regardless of the name, these "modes" affect API requests to/from the device including push notifications.

Steps to check:

1. Plug the device in to start charging.
   1. This will help bypass any power management settings discussed below in the platform specific sections.
2. Turn off "Power saving" and "Low power mode" on the device.
3. Open the app or browser on the device and keep it in focus.
4. Send your subscription a push notification.

Platform specific reasons for delays

Below are some platform-specific reasons for push delays if the above steps do not help.

Mobile web push: Chrome, Firefox, etc

Allow background modes

You may get delays or not push at all if the browser does not have background data usage enabled.

On your Android device, navigate to Settings > Apps > your browser > Mobile data and enable Allow background data usage.

You can also select Allow data usage while Data saver is on if you keep your device on the power saving settings.

Storage and cache

If your browser app storage and/or cache is full, this could cause delays or no push to show at all.

On your Android device, navigate to Settings > Apps > your browser > Storage.

WARNING: clearing data and/or cache will likely prevent push from showing again. After doing this, you will need to return to the site and if you have Auto Resubscribe enabled, you will get resubscribed with a new web push subscription. See Web push setup for details.

Unfortunately this is a device/browser limitation and not related to OneSignal or any other push provider.

FCM: Android & chrome

Android 9+ introduced new power management settings that can affect both mobile and web push notifications. If you follow the steps in the above Power saving, focus, and low power modes like plugging your phone into a charger and having the app open and in-focus when sending the message, that should bypass most of these power management features.

If you are sending too many high priority messages, you could be getting rate limited or reduced priority by FCM which could delay messages. It's important to understand and follow the best practices to Optimize for Doze and App Standby.

APNS: iOS & safari

Items to check if using a mac, iPhone, or iPad.

Wifi: Low data mode

Navigate to your Settings > Wifi and check if "Low data mode" is turned on. Try turning this off to see if it helps.

Mobile apps: Background notifications and custom code

Consistent delays of around 30 seconds can occur if you are using custom code within the Notification Service Extension. You should follow our Mobile SDK Setup docs to verify you have both the OneSignalNotificationServiceExtension and App Groups setup according to our guide. If you have customizations within your own NotificationServiceExtension, make sure that you are still implementing our provided code and passing in your notification updates to the OneSignalExtension.didReceiveNotificationExtensionRequest() completion handler.

Background (aka silent or data) notifications, without a message body, are sent at a normal priority instead of high due to Apple's limitations. These can be delayed by a few minutes.

Development builds of your app with connect to Apple's Sandbox APN server which may be slower. We recommend testing with release mode such as with an ad-hoc or test flight build so your app will use Apple Production APN server to rule out any delays their Sandbox server could cause.

Notification media attachments, adding an image to your notification could delay it up to 30 seconds as it downloads it. Try omitting your image temporarily to rule this factor out.

Getting support

Push notification delay issues are generally rare and temporary. Once the push is sent from OneSignal, it can difficult to pinpoint the actual reason why some users get it delayed and some do not. The above lists almost every reason why this can occur.

If you are not getting notifications at all, see our Mobile push: Notifications not shown or Web push: Notifications not shown docs.

If you are having issues with delays, you can reproduce it consistently, and you have followed the above troubleshooting steps, then please reach out to our support team with the following details:

1. The OneSignal app ID you are testing.
2. The OneSignal subscription ID you tested with.
3. The OneSignal notification IDs you sent to your subscription or provide the link to the message report from within your OneSignal dashboard.
4. Which of the above steps you followed and any screenshots if you can.

We would be happy to assist further.