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Titre
SQL Server error: "The prelogin packet used to open the connection is structurally invalid; the connection has been closed..." -
Description
The below errors appear in the SQL error log and Foglight agent log:SQL error log:"SQL Server Fatal Current Process Error (severity level 20)SQL Server instance <xxxx> raised the following Fatal message: Error: 17828, Severity: 20, State: 3. "The prelogin packet used to open the connection is structurally invalid; the connection has been closed. Please contact the vendor of the client library.".Note: Error can be traced to Foglight Agent Manager host
Foglight agent log:com.quest.qsi.fason.framework.connections.jdbc.JDBCConnectionImpl - Failed to create new connection. [MSSQLProfile{host='SQLInstance.MyCoDomian.com', instance= 'DEFAULT_INSTANCE', username='MYCompany\SvcAccount', authType= 'WINDOWS_CUSTOM', port= '11011' useNTLMv2= 'true', socketTimeout= '900', secureConnection= 'OFF' }][Foglight][SQLServer JDBC Driver]The SQL Server login requires an SSL connection. -
Cause
CAUSE 1
SSL option on the DBSS agent is OFF (or OPTIONAL in the Agent Status Properties) so that the agent is unable to connect to to Forced Encryption setting on SQL Server instance.
NOTE: In the Agent Status Properties of SQL Server agents an OPTIONAL option is included. When the OPTIONAL method (negotiate) is used, timeouts may also occur for various reasons and the connection may fall back to a non-SSL connection string.CAUSE 2
Two SQL Server agents were monitoring the same host from different Agent Managers.
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Résolution
RESOLUTION 1
- Turn on the Use SSL checkbox in the Connection Details panel for SQL Server instances or set the SSL Connection pulldown field to Mandatory in Agent Status for agents where Forced Encryption is enabled on a SQL Server instance.
- Deactivate the SQL Server agent in Agent Status and then reactivate the agent to reset agent manager client connection.
- Check the SQL Server Error Log files to ensure that the same log print as above does not reoccur.
- Ensure that other SQL clients (third party) are not also trying to connect via Plain Text connection and fix their connection strings.
RESOLUTION 2
Deactivate any duplicate SQL Server agents that are monitoring the same host.
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Informations supplémentaires
This specific error is informational and should not impact SQL Server performance. If this is happening outside of Foglight, review any other connections to the instance, especially those identified in any CLIENT source messages. For messages that occur regularly at timed intervals, check for SQL jobs or security scanning software connecting to the host.