MDW Data Collector Server Activity collection step 3 suddenly stopped working
This error:


  0x80040E14 Description: "The handle that was passed to dm_exec_sql_text was invalid."


indicates a "handle" was passed into the sys.dm_exec_sql_text function that was not an actual, valid, SQL handle.   

You'll see this error if you run this code:

SELECT *
FROM sys.dm_exec_sql_text(0)


sys.dm_exec_sql_text is used to obtain the query text for queries that reside in the plan cache, and can be seen in action via this sample code:

SELECT TOP(10)
    decp.plan_handle
    , dest.text
FROM sys.dm_exec_cached_plans decp
CROSS APPLY sys.dm_exec_sql_text(decp.plan_handle) dest;


It looks like the data collector has a bug; what version of SQL Server do you have installed?