Code to replace deprecated sp_who

select blocking_session_id, wait_duration_ms, session_id

from sys.dm_os_waiting_tasks

where blocking_session_id is not null

or

SELECT

        t1.resource_type,

        t1.resource_database_id,

        t1.resource_associated_entity_id,

        t1.request_mode,

        t1.request_session_id,

        t2.blocking_session_id

FROM sys.dm_tran_locks AS t1

INNER JOIN sys.dm_os_waiting_tasks AS t2

    ON t1.lock_owner_address = t2.resource_address;