If the client certificate on a user's mobile device expires, you can do either of the following. Note that the actions in this article need to be carried out by a cybozu.cn administrator.

If you want the user to continue to use client certificate authentication after their client certificate has expired, their client certificate needs to be reissued. You cannot extend the expiration date of an existing client certificate.
For the steps to reissue a client certificate, refer to the following page.
Configuring client certificate authentication

If you want to disable access to a mobile device after its client certificate has expired, use either of the following methods.

• Change the user's password and deactivate their client certificate
  Changing the user's password will log them out of kintone and prevent them from accessing the service on their mobile device. This also prevents kintone mobile from sending push notifications to the device.
  In addition to changing the user's password, it is also necessary to deactivate their client certificate.

  • Changing user passwords
  • Stopping the use of client certificate authentication

• Deactivate the user
  Deactivating the user in Users & system administration will disable their access to kintone.
  Deactivating users