What should I do if the sender of the message certificate is prompted to be invalid after the remote push message certificate is registered for iOS?

What should I do if the sender of the message certificate is prompted to be invalid after the remote push message certificate is registered for iOS?

We need to register a certificate when writing an App for remote message pushing. We can go to the Certificates, Identifiers & Profiles page of the Apple development website to create an App ID first.

Enter the Push Notifications option, and select create Certificate in its subitem Development SSL Certificate (because the Certificate is used for debugging, it is created in Development, there is also a certificate under Distribution, which should be created before release. We can ignore it here ).

You need to upload a cer Certificate file. You need to create a certificate locally.

The procedure is as follows: Open the certificate Assistant in the key string Access Program in the system-> request Certificate options from the Certificate Authority:

Next, store it on the disk:

Then upload the generated Certificate file to the Apple development website, and a new certificate will be generated. We will download it to the local device and double-click it to import it to the key string.

Open the key string and find the certificate you just imported. The name is similar to "Apple Development IOS Push Services: name of your App Id". Then you may find a small red line shown above: the issuer of this certificate is invalid.

The solution is simple:
0. First, update the WWDR System Certificate. Go to https://developer.apple.com/certificationauthority/applewwdrca.certo download the cerdownloaded file and double-click the key string.
1. select "Log on" in the key string and click "certificate". On this page, choose "display"> "display expired certificates" on the toolbar. At this time, you will find an expired Apple Worldwide Developer Relations Certification Authority, delete it
2. the expired Apple Worldwide Developer Relations Certification Authority is also available in the system column.
3. Now let's take a look at the issuer's status. The Green "valid certificate" is displayed: