SQL Server 2017

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CREATE TABLE dbo.myTable
(
  RowID     int         NOT NULL,
  DateStamp datetime    NOT NULL,
  Success   bit         NOT NULL,
  Error     varchar(50) NOT NULL
);
INSERT INTO
  dbo.myTable (RowID, DateStamp, Success, Error)
VALUES
  (1001, '5/24/2019 11:23am', 1, 'None'),
  (1004, '5/24/2019 11:24am', 1, 'None'),
  (1005, '5/24/2019 11:25am', 1, 'None'),
  (1009, '5/24/2019 11:26am', 0, 'SQL Timeout'),
  (1018, '5/24/2019 11:27am', 0, 'SQL Timeout'),
  (1019, '5/24/2019 11:28am', 1, 'None'),
  (1026, '5/24/2019 11:29am', 1, 'None'),
  (1035, '5/24/2019 11:30am', 0, 'Planned Maintenance'),
  (1100, '5/24/2019 11:31am', 0, 'Planned Maintenance'),
  (1111, '5/24/2019 11:32am', 1, 'None')
;
10 rows affected

WITH
  sentinels AS
  (
    SELECT
      DateStamp,
      Success,
      Error,
      Grp = CASE
              WHEN Success = LAG(Success) OVER (ORDER BY DateStamp ASC)
               AND Error   = LAG(Error  ) OVER (ORDER BY DateStamp ASC)
              THEN 0
              ELSE 1
            END
    FROM
      dbo.myTable
  ),
  fullyMarked AS
  (
    SELECT
      DateStamp,
      Success,
      Error,
      Grp = SUM(Grp) OVER (ORDER BY DateStamp ASC ROWS UNBOUNDED PRECEDING)
    FROM
      sentinels
  )
SELECT
  Starting  = MIN(DateStamp),
  Ending    = MAX(DateStamp),
  Polls     = COUNT(*),
  Success,
  Error
FROM
  fullyMarked
GROUP BY
  Success,
  Error,
  Grp
ORDER BY
  Starting ASC
;


Starting
Ending
Polls
Success
Error


2019-05-24 11:23:00.000
2019-05-24 11:25:00.000
3
True
None

2019-05-24 11:26:00.000
2019-05-24 11:27:00.000
2
False
SQL Timeout

2019-05-24 11:28:00.000
2019-05-24 11:29:00.000
2
True
None

2019-05-24 11:30:00.000
2019-05-24 11:31:00.000
2
False
Planned Maintenance

2019-05-24 11:32:00.000
2019-05-24 11:32:00.000
1
True
None

Starting	Ending	Polls	Success	Error
2019-05-24 11:23:00.000	2019-05-24 11:25:00.000	3	True	None
2019-05-24 11:26:00.000	2019-05-24 11:27:00.000	2	False	SQL Timeout
2019-05-24 11:28:00.000	2019-05-24 11:29:00.000	2	True	None
2019-05-24 11:30:00.000	2019-05-24 11:31:00.000	2	False	Planned Maintenance
2019-05-24 11:32:00.000	2019-05-24 11:32:00.000	1	True	None