Error while sending push notifications on iOS devices

Error while sending push notifications on iOS devices

Gents, 
Push notifications working well on Android devices but not the iOS. as per the serverout0.txt log i'm seeing that APN certificate expired 
[07:22:11:570]|[08-13-2020]|[SYSOUT]|[INFO]|[152]: 0 [JavaPNS grouped notification thread in QUEUE mode] INFO javapns.notification.PushNotificationManager  - Attempt failed (Received fatal alert: certificate_expired)... trying again
|
[07:22:11:657]|[08-13-2020]|[com.manageengine.servicedesk.notification.realtimenotification.ExpiredMessagesDeleteThread]|[INFO]|[130]: Deleted 0 chat messages at1597292531657|
[07:22:12:248]|[08-13-2020]|[SYSOUT]|[INFO]|[152]: 681 [JavaPNS grouped notification thread in QUEUE mode] INFO javapns.notification.PushNotificationManager  - Attempt failed (Received fatal alert: certificate_expired)... trying again
|
[07:22:12:902]|[08-13-2020]|[SYSOUT]|[INFO]|[152]: 1335 [JavaPNS grouped notification thread in QUEUE mode] ERROR javapns.notification.PushNotificationManager  - Attempt to send Notification failed and beyond the maximum number of attempts permitted
|
[07:22:12:904]|[08-13-2020]|[SYSOUT]|[INFO]|[152]: 1337 [JavaPNS grouped notification thread in QUEUE mode] ERROR javapns.notification.PushNotificationManager  - Delivery error
javax.net.ssl.SSLHandshakeException: Received fatal alert: certificate_expired
at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
at sun.security.ssl.Alerts.getSSLException(Alerts.java:154)
at sun.security.ssl.SSLSocketImpl.recvAlert(SSLSocketImpl.java:2033)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1135)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1385)
at sun.security.ssl.SSLSocketImpl.writeRecord(SSLSocketImpl.java:757)
at sun.security.ssl.AppOutputStream.write(AppOutputStream.java:123)
at java.io.OutputStream.write(OutputStream.java:75)
at javapns.notification.PushNotificationManager.sendNotification(PushNotificationManager.java:427)
at javapns.notification.PushNotificationManager.sendNotification(PushNotificationManager.java:366)
at javapns.notification.transmission.NotificationThread.runQueue(NotificationThread.java:266)
at javapns.notification.transmission.NotificationThread.run(NotificationThread.java:202)
at java.lang.Thread.run(Thread.java:748)
|
[07:22:12:904]|[08-13-2020]|[SYSOUT]|[INFO]|[152]: 1337 [JavaPNS grouped notification thread in QUEUE mode] ERROR javapns.notification.PushNotificationManager  - Delivery error: javax.net.ssl.SSLHandshakeException: Received fatal alert: certificate_expired
|

Please your assistance get this fixed. 

                  New to ADSelfService Plus?