Crossmint will be migrating our testnet RPC nodes to use the goerli testnet instead of rinkeby. Here is what you need to do to enable goerli support now in your testing.
As long as this docs page is live you'll need to setup your Crossmint collection in: https://goerli.crossmint.io/console instead of our staging system.
The good news is your existing staging developer account is enabled here. You will also be able to see any other collections you've created here.
Set up your collection as normal in the Ethereum tab of the create-collection section of the console.
The only other thing you need to do is update the button code you deploy to your test site so the environment is set to https://goerli.crossmint.io instead of staging. Here is a sample button config using the latest version of the sdk: