This article was previously published under Q243050
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BUG #: 18843 (SQLBUG_65)
Microsoft SQL Server 6.5 may return the following 1203 error, which is then followed by other errors that indicate the client was disconnected.
Server: Msg 1203, Level 20, State 2, Line 1 Caller of lock manager is incorrectly trying to unlock an unlocked object. spid=10 locktype=4 dbid=2 lockid=16003088.
This error occurs if the following conditions are met:
The SQL Server is a post service pack 5 (SP5) build between 433 and 456.
The user session or the server use trace flag 5302.
The query uses SELECT INTO.
The query contains a UNION.
The second SELECT of the UNION contains an aggregate function (for example, SUM).
Avoid the conditions listed in the SYMPTOMS section. For example, avoid the UNION by using INSERT ... SELECT for the second query in the UNION.
Microsoft has confirmed this to be a problem in SQL Server version 6.5. This problem has been corrected in the Post Service Pack 5a Update for Microsoft SQL Server version 6.5. To install the Post Service Pack 5a Update, you must have either SQL Server 6.5 SP5 or SP5a installed.
For information about how to download and install the SQL Server 6.5 Service Pack 5a, refer to the following article in the Microsoft Knowledge Base:
197177 INF: How to Obtain SQL Server 6.5 Service Pack 5a
If you already have SQL Server 6.5 SP5 or SP5a installed, you can download the Post SP5a Update from the following article in the Microsoft Knowledge Base:
274036 INF: How to Obtain SQL Server 6.5 Post Service Pack 5a Update
For more information, contact your primary support provider.