Unable to create a snapshot

D:\EasySearch10.1\elasticsearch-curator-5.8.1-amd64\curator-5.8.1-amd64>curator_cli --host 192.168.38.115 snapshot --repository repo1 --name snapshot30jan indices --filter_list '{"filtertype":"none"}'
Usage: curator_cli snapshot [OPTIONS]

Error: Invalid value for "--filter_list": Filter list is invalid JSON: '{filtertype:none}'

That's because you're using Windows. Windows handles single and double quoted objects differently.

Try following the example in this issue.