I was using databricks scopes, to get the key which was used in the the config. I received a similar mount error while mounting with "wasbs" driver,  "ExecutionError: An error occurred while calling o427.mount.", this was the issue because the scope was not defined correctly, after creating a new scope it solved the error.

If the requirement is not using scopes, a simple script like this worked for me

container_name = "<container_name>"
storage_account = "<storage_account>"

url = "wasbs://" + container_name + "@" + storage_account + ".blob.core.windows.net/"
config = "fs.azure.account.key." + storage_account + ".blob.core.windows.net"
key = "<storage_account_key>"

mount_folder = "/mnt/newmnt"
dbutils.fs.mount(source = url, mount_point = mount_folder, extra_configs = {config : key})