PushNotification not working

Hi, I have a problem with push notification on iOS, the notification is displayed when the app is runnning but, when it is in background, nothing happen. Server side I have this error:

Push ➔ debug Could not send notification id: “undefined”, Error: Cannot read property ‘send’ of undefined
Push ➔ debug TypeError: Cannot read property ‘send’ of undefined
at sendAPN (app/push/server/apn.js:48:16) at PushClass.sendNotificationNative (app/push/server/push.js:87:5)
at app/push/server/push.js:208:16
at SynchronousCursor.forEach (packages/mongo/mongo_driver.js:1138:16)
at Cursor. [as forEach] (packages/mongo/mongo_driver.js:918:44)
at PushClass.sendNotification (app/push/server/push.js:201:35)
at PushClass.send (app/push/server/push.js:325:9)
at PushNotification.send (app/push-notifications/server/lib/PushNotification.js:70:15)
at NotificationClass.push (app/notification-queue/server/NotificationQueue.ts:95:20)
at app/notification-queue/server/NotificationQueue.ts:67:12
at /opt/Rocket.Chat/programs/server/npm/node_modules/meteor/promise/node_modules/meteor-promise/fiber_pool.js:43:40

Had same issue on 4.8.7
Private key and/or format how it was pasted into config was wrong.

Exporting apple push certificate from .p12
openssl pkcs12 -in cert.p12 -out newfile.crt.pem -clcerts -nokeys
openssl pkcs12 -in cert.p12 -out newfile.key.pem -nocerts -nodes

Then putting the full output into Push configuration,
Format like

Bag Attributes
friendlyName: something
localKeyID: 7D EE 03 27 E2 00 7D 88 BC 01 BE 75 C5 00 B7 59 00 7E 2A 64
Key Attributes:
-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----

Bag Attributes
friendlyName: Apple Push Services: com.something.something
localKeyID: 7D EE 03 27 E2 AD 7D 88 00 00 BE 00 C5 DC B7 59 8F 7E 2A 64
subject=/UID=com.cradon.radonm/CN=Apple Push Services: com.something.random/OU=HV67G3ZRG7/O=Company or something/C=US
issuer=/CN=Apple Worldwide Developer Relations Certification Authority/OU=G4/O=Apple Inc./C=US
-----BEGIN CERTIFICATE-----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xXj
QREmqklNywCiHKoGy7u0c07JP+kXgDyUDWfzzoI7
-----END CERTIFICATE-----

Works for me