Steps to reproduce:

1. Tried to add SMART monitoring for Windows hosts by adding template "SMART by Zabbix agent 2"
2. Install last Zabbix agent 2 on host, install last smartmontools with defaults
3. Try to check or monitor like this:

.\zabbix_get.exe -k smart.disk.get -s 127.0.0.1

Result:

ZBX_NOTSUPPORTED: Cannot fetch data: Failed to scan for devices: Cannot unmarshal JSON: invalid character '\'' looking for beginning of value..

Expected: Valid data

Extra info: Executing of

.\zabbix_agent2.exe -t smart.disk.get

 gives valid output.

According to Edgar`s comment, Plugins.Smart.Path is mandatory and have to be configured in plugin confiration file or specific environment for smartmontools (smartctl) have to be configured in system. There is no documented requirement for it in template or plugin description.