The app's App Service plan must be in the Basic, Standard, Premium, or Isolated tier.The free certificate comes with the following limitations: Doesn't support wildcard certificates. Doesn't support usage as a client certificate by using certificate thumbprint, which is planned for deprecation and removal. Doesn't support private DNS. Isn't exportable. Isn't supported in an App Service Environment (ASE). Only supports alphanumeric characters, dashes (-), and periods (.). Only custom domains of length up to 64 characters are supported.
