I am scratching my head for quite a few hours now. When i run the script:

select XEventData.XEvent.value('(data/value)[1]', 'varchar(max)') as DeadlockGraph

FROM

(select CAST(target_data as xml) as TargetData

from sys.dm_xe_session_targets st

join sys.dm_xe_sessions s on s.address = st.event_session_address

where name = 'system_health') AS Data

CROSS APPLY TargetData.nodes ('//RingBufferTarget/event') AS XEventData (XEvent)

where XEventData.XEvent.value('@name', 'varchar(max)') = 'xml_deadlock_report'

I get invalid information for deadlocks. Example:-

<deadlock>

<victim-list />

<process-list>

It misses out on the victim-processid field and when i try to open this graph up on SSMS, i get "Failed to Initialize Control. Key cannot be null. Parameter name: key"

This is only on 1 of the servers. Version is Microsoft SQL Server 2008 R2 (SP2) - 10.50.4000.0 (X64).