【文章內(nèi)容簡介】 u to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk. 1. Make sure that the instance of SQL Server is configured to use Windows authentication and SQL Server Authentication. To do so, make sure that the following registry keys are on the puter that is running SQL Server. For the default instance of SQL Server: HKEY_LOCAL_MACHINE\Software\Microsoft\MSSQLServer\MSSQLServer\LoginMode For the named instance of SQL Server: HKEY_LOCAL_MACHINE\Software\Microsoft\Microsoft SQL Server\Instance Name\MSSQLServer\LoginMode Make sure that the following registry key values are set: Authentication type Value 大連交通大學(xué) 2020屆本科生畢業(yè)設(shè)計（論文）外文翻譯 7 Windows authentication only 1 Mixed mode (SQL Server Authentication and Windows authentication) 2 Note If you make any changes to the registry, you must stop and then restart the instance of SQL Server for the changes to take effect. 2. Try to connect to the instance of SQL Server by using different Windows accounts or SQL Server login accounts. This can help determine if the connection is not successful because of problems with a particular login account. For example, the password of the login account may have been changed. 3. Try to connect to the instance of SQL Server by using different protocols. For example, the connections that use the TCP/IP protocol with Windows authentication may not be successful, but connections that use the named pipes protocol with Windows authentication may be successful. If you are using certificates, you may receive a Secure Sockets Layer (SSL) security error message when you try to connect to the instance of SQL Server. Troubleshoot stress on TCP/IP sockets When you use the SQL Server ODBC driver, the Microsoft OLE DB Provider for SQL Server, or the managed provider, you can disable connection pooling by using the appropriate application programming interfaces (APIs). When you disable connection pooling and your application frequently opens and closes connections, the stress on the underlying SQL Server work library may increase. Sometimes, the Web servers and the JDBC drivers may also try to connect to the instance of SQL Server. Therefore, the increase in connection requests to SQL Server may be more than SQL Server can handle. This may stress the TCP/IP sockets, and you may receive the following error message in the SQL Server error log file: 20200807 20:46: server Error: 17832, Severity: 20, State: 6 20200807 20:46: server Connection opened but invalid login packet(s) sent. Connection closed. For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base: 154628 INF: SQL logs 17832 with multiple TCP\IP connection requests 328476 TCP/IP settings for SQL Server drivers when pooling is disabled Note You may not notice the stress on TCP/IP sockets if you are running SQL Server 2020 SP3 or SQL Server 2020 SP3a because a limit on the number of login packets was added. The 17832 error occurs when you use thirdparty drivers to connect to the 大連交通大學(xué) 2020屆本科生畢業(yè)設(shè)計（論文）外文翻譯 8 instance of SQL Server. To resolve this problem, contact the thirdparty vendor and obtain drivers that have been tested to work with SQL Server 2020 SP3 and SQL Server 2020 SP3a. See if the instance of SQL Server is started in singleuser mode If the instance of SQL Server that you are trying to connect to is started in singleuser mode, only one connection can be established with SQL Server. If you have software running on your puter that automatically connects to SQL Server, the software can easily use the only connection. For example, the following software can automatically connect to the instance of SQL Server: ? SQL Server Agent ? Thirdparty backup software ? Thirdparty monitoring software ? Thirdparty virus software ? Microsoft Inter Information Services (IIS) ? SQL Server Enterprise Manager The client application that is trying to connect to the instance of SQL Server receives the following error message: SQL Server does not exist or Access Denied This error generally occurs during SQL Cluster Setup and service pack setup when the setup process starts the instance of SQL Server in singleuser mode. The specified applications may automatically connect to the instance of SQL Server using the only available connection, and setup is not successful. To determine if the instance of SQL Server has been started in singleuser mode, check to see if the SQL Server error log file has an entry that is similar to following: 20200731 11:26: spid3 Warning ****************** 20200731 11:26: spid3 SQL Server started in single user mode. Updates allowed to system catalogs. Verify named pipes connectivity to SQL Server If you cannot connect to the instance of SQL Server by using named pipes, make sure that the instance of SQL Server is configured to accept named pipes connections. Troubleshoot connections that time out during the recovery process Every time that you start an instance of SQL Server, SQL Server recovers each database. During this recovery process, SQL Server rolls back the transactions that are 大連交通大學(xué) 2020屆本科生畢業(yè)設(shè)計（論文）外文翻譯 9 not mitted. SQL Server also rolls forward the transactions that are mitted and the changes that were not written to the hard disk when the instance of SQL Server was stopped. When the recovery process is plete, SQL Server logs the following message in the SQL Server error log file: Recovery Complete During the recovery process, SQL Server may not accept connections. Clients that try to connect to the instance of SQL Server during that time may receive an error message that is similar to the following: Timeout Expired The SQL Server Agent servi