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I've found this guy in my SQL log:

"The prelogin packet used to open the connection is structurally invalid; the connection has been closed. Please contact the vendor of the client library. [CLIENT:]

Error: 17828, Severity: 20, State: 4."

but I can't find any information on it.

We are running SQL 2005 Enterprise (x86) - SP2 and the error is coming from the AD server. The users are getting errors on the application side - "Connection failure". It's random too and I can't reproduce it.

Does anyone know how to fix this (besides 'contact the vendor')?

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up vote 5 down vote accepted

It's a timeout error, basically, and it's fixed (i.e. error suppressed) in SS 2008.

Here's the relevant connect item.

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