Manually fixing CryptographicException when trying to read function keys

If the encryption keys are gone, then there is no way to decrypt that information. You can either delete all the files and they'll be auto generated by the runtime again with new keys or change the key values in the files manually and set the encrypted flag to false.

To delete all the keys files you'll need to connect to the SCM end point of your function app through https://<functionAppName>.scm.azurewebsites.net/DebugConsole use the same login account you use for the azure portal

Then navigate to D:\home\data\Functions\secrets and delete all the files there.