The information in this article applies to:
- Microsoft SQL Server, versions 4.2x, 6.0, and 6.5
SUMMARY
Under certain situations, Microsoft SQL Server may log the following error
either in its errorlog or in the Windows NT event log:
17832 Unable to read login packet(s).
This error occurs if a client starts to connect but never successfully
completes the attempt because of a client operating system, application, or
network failure. Wide area networks (WANs) are more susceptible than local
area networks (LANs) to this type of problem, because such networks often
have many routers and other network devices that can delay data packet
delivery and/or cause other difficulties in the delivery of data packets
due to improper packet fragmentation or misrouting.
However, the very occurrence of these errors in the errorlog or event log
does not necessarily indicate any real problems with your SQL Server
connectivity. Even in normal operations, this error may still occur at
times, due to the unreliable nature of networks, especially wide area
networks. In addition, improper use of applications (such as restarting the
computer in the middle of a login process) can also cause this error to
occur.
To determine whether or not you are facing a real problem, you may want to
check the following:
- Check with the end users to see whether they have experienced any
difficulties in making connections to SQL Server. If nobody reports any
connectivity problems, you can usually ignore these errors.
- Check the frequency of this error in the errorlog. If it occurs very
frequently, it indicates some potential problems, even if no one is
complaining about any connectivity problems.
If you have determined that you have a real problem, you may want to apply
the additional troubleshooting methods described in the remainder of this
article.
MORE INFORMATION
Errors of type 17832 can generally be classified into two categories:
- Frequent, repeated occurrence of these errors. If you examine the
timestamps of these errors, you may find that they usually occur in
regular intervals, typically one or more occurrences per second. The
errorlog typically is full of these errors. This is mostly caused by
client-side problems such as operating system or network software. The
repeated occurrence of these errors is caused by the connection retries
built into the client-side DB-Library or ODBC, which does not stop until
the client application times out.
- Intermittent, random occurrence of these errors. In the errorlog, you
will find these errors occurring once in a while without any regularity.
If nobody has reported any connectivity problems, you can generally
ignore these errors. If someone did report connectivity problems to SQL
Server, you need to use the timestamps to determine whether these
reported problems correspond to the errors of type 17832 in the
errorlog.
Because SQL Server does not know the client's address or host name yet when
the error occurs, this error message cannot provide any information about
which client causes the error. Therefore, it can be very time consuming to
troubleshoot this error, especially if it occurs only intermittently. If
you cannot identify which client computer is likely causing the error, you
may have to use network sniffing tools such as Network General's Sniffer or
Microsoft's Network Monitor to capture the sniffer trace for further
analysis. The best approach is to check the following known issues first,
and contact Microsoft SQL Server Support if none of following causes
matches your case.
Error 17832 can be caused by:
- A Windows 95 Winsock issue. A 16-bit Windows application using TCP/IP
sockets may encounter this problem under Windows 95 in a slow network
environment. The error is repeated numerous times in the errorlog. For
more information, see the following article in the Microsoft Knowledge
Base:
ARTICLE-ID: Q164516
TITLE : INF: Error 17832 Caused by Blocking Timeout in 16-Bit
Sockets
- Some anti-virus software on named pipes clients. Typically, when you
configure anti-virus software to scan all files, named pipes (which are
considered files) may be affected adversely. In this case, named pipes
may be opened in invalid mode, causing these errors on the server side.
To correct this problem, uninstall the anti-virus software to verify
that this is indeed the case, and contact the software vendor for
information on how to disable the auto-scanning of named pipes.
- The use of the 32-bit ODBC driver for 16-bit Windows application under
Windows 95. The 32-bit ODBC driver for SQL Server is not supported for
use with 16-bit applications under Windows 95. The error occurs
repeatedly in the errorlog for the duration of client login. For more
information, see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q140697
TITLE : INF: Win16 ODBC Applications in a Win32 Environment
- Insufficient system resources on the client side. If a client's request
for opening connections fails due to insufficient resources on the
client computer, the open connection function returns with an error
status, and no login packets are sent as a result, causing these errors.
For more information on this known issue, see the following article in
the Microsoft Knowledge Base:
ARTICLE-ID: Q161169
TITLE : BUG: "Too Many Open File Handles" Error Using Named Pipes
- Insufficient system resources on the server side. If SQL Server, the
Windows NT operating system, or network services cannot allocate enough
resources to complete new connections, the connections are reset by
server, thereby causing these errors to occur. For more information on
this known behavior, see the following article in the Microsoft
Knowledge Base:
ARTICLE-ID: Q154628
TITLE : INF: SQL Logs 17832 With Multiple TCP\IP Connection
Requests
- A client interruption in the middle of a login process. If a client
application does not wait until the login process finishes, and either
the application is stopped or the client computer is restarted, this
error may occur each time such an abnormal termination happens.
- An ODBC application that times out. There is a small window of
opportunity in the SQL Server ODBC driver that may cause these errors
when the ODBC application times out. Typically this error occurs when
the application's timeout setting is just a small bit longer than the
actual time it takes to complete the login process.
- Some routers' configurations in a routed network not allowing bigger
data packets to go through properly. This is often caused by incorrect
router configurations, "black hole" routers, or unreliable networks such
as RAS connections. For TCP/IP networks, you can generally use the
TCP/IP PING utility with the "-l" parameter to test this case, but more
complex issues may require the use of network sniffing tools to analyze
the bottleneck. For more information on some relevant issues, see the
following articles in the Microsoft Knowledge Base:
ARTICLE-ID: Q159211
TITLE : Diagnoses and Treatment of Black Hole Routers
ARTICLE-ID: Q136970
TITLE : PMTU Black Hole Detection Algorithm Change for
Windows NT 3.51
- The Network being too slow or unreliable. In a WAN or heavily routed
network, it may take many retransmissions to deliver a large data packet
successfully. If such a delivery of SQL Server login packets takes more
than 45 seconds, this error will occur every time. The only solution in
this case is to tune or upgrade the network; otherwise, the network is
too slow for any meaningful SQL Server applications.
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