【正文】 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: 20210731 11:26: spid3 Warning ****************** 20210731 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 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 7 The SQL Server Agent service may not start because it waits for SQL Server to recover the databases. Therefore, when you receive the following message in the SQL Server error log file, the connections will no longer fail with a timeout error: Recovery Complete If the recovery process takes a long time, you may have to additionally troubleshoot the recovery process. Test different ways to connect to the instance of SQL Server If you experience connectivity problems when you connect to the instance of SQL Server, you can use one or more of the following methods to work around the connectivity problem. ? Test the connectivity to the instance of SQL Server by using both SQL Server Authentication and Windows authentication. ? Test the connectivity to the instance of SQL Server from other data sources, such as an ODBC DSN, a .udl file, SQL Query Analyzer, SQL Server Enterprise Manager, the isql utility, or the osql utility. ? Test the connectivity to the instance of SQL Server by using different protocols. You can specify different protocols by creating a new alias for the instance of SQL Server using that protocol. You can also specify the protocol in your connection string by adding tcp:, np:, lpc:, or rpc: to the beginning of the name of the instance of SQL Server. For example, if TCP/IP connections are not successful, named pipes connections succeed. ? Test the connectivity by using a different login account to help you determine if the problem is associated with a particular login account. ? Try to add an entry that corresponds to the IP address of the puter that is running the instance of SQL Server to the %systemroot%\system32\drivers\etc\hosts file. ? Try to connect to the instance of SQL Server from the puter that is running SQL Server and from the client. ? If you are connecting from the puter that is running SQL Server, you can specify . or (local) (without the quotation marks) instead of the server name and then connect. ? Try to connect to the instance of SQL Server by using the IP address instead of the server name. ? Try to specify the specific port that the instance of SQL Server is listening on, either by creating an alias or by adding a port number to the connection string (MyServer\MyInstance, 1433, for example). Capture work monitor traces If the connectivity problem is not resolved by the steps that are mentioned in Test different ways to connect to the instance of SQL Server 2021 section, use the Network Monitor utility to capture work traces. To obtain more detailed information, you may have to use SQL Profiler traces. You can also use the Network Diagnostics Tool for nonclustered puters that are running SQL Server for work tracing. 8 B2 中文譯文 如何解決 SQL Server 2021 中的連接問題 Chris Tull, Microsoft Help and Support 這一篇文章能幫助你解決微軟 SQL 伺候器 2021 的連接性問題。username39。因此，讓一個客戶端對一部服務器計算機連接，客戶端一定使用一個客戶端網(wǎng)絡(luò)庫，該網(wǎng)絡(luò)庫匹配與 SQL Server 實例正在使用的服務器網(wǎng)絡(luò)庫之一 。 b. 指向 “Microsoft SQL Server”，然后單擊 “客戶端網(wǎng)絡(luò)實用程序 ”。如果端口正被其他應用程序使用，或者如果你正在嘗試使用一個錯誤的 IP 地址進行連接，就可能會出現(xiàn)此問題。要使用 Tel 程序，在命令提示符下運行下列命令： Tel IP Address Port Number 如果 Tel 程序沒有成功，并且你接收到錯誤信息，請解決此錯誤然后嘗試再次連接。username39。有時， Web 服務器和 JDBC 驅(qū)動程序也會嘗試連接到 SQL Server 實例。 測試連接到 SQL Server 實例的不同方法 當你連接到 SQL Server 實例時，如果遇到了連接問題，可以使用下面的一種或多種方法來解決連接問題。 ? 嘗試指定 SQL Server 實例正在偵聽的特定端口。當停止 SQL Server 實例時， SQL Server 還將前滾已提交的事務和沒有寫入硬盤的更改。例如，使用 TCP/IP 協(xié)議進行 Windows 身份認證的連接可能會失敗，但是使用命名管道協(xié)議進行 Windows 身份認證的連接就可能會成功。 ? 域之間的信任關(guān)系出現(xiàn)問題。因此，可能無法連接到命名實例。在默認情況下，一個 SQL Server 實例默認偵聽端口 1433。 啟用的協(xié)議和別名的驗證 如果客戶端計算機上的別名錯誤設(shè)置，可能會引起連接問題。你能配置服務器網(wǎng)絡(luò)的特性使用服務器網(wǎng)絡(luò)公用程序()的網(wǎng)絡(luò)控件庫屬性。NTAUTHORITY\ANONYMOUS LOGON39。 然而 , 當客戶 端 申請和 SQL Server 的例證在不同的計算機 ， 網(wǎng)絡(luò) IPC（ 像是 TCP/IP上住的時候或者命名管道 ） 用來溝通。為此，請遵從如下步驟操作： 1. 單擊 “開始 ”，然后單擊 “運行 ”。 10 3. 單擊 “別名 ”標簽，然后驗證為 SQL Server 實例所配置的別名。在這種情況下，請確認客戶端應用程序也被設(shè)置為動態(tài)地決定端口。 Login failed for user 39。 1. 請確認 SQL Server 實例配置為使用 Windows 身份認證和 SQL Server 身份認證。 查看 SQL Server 實例是否以單用戶模式啟動 如果嘗試連接的 SQL Server 實例是以單用戶模式啟動的，只能建立一個到 SQL Server 的連接。還可以通過在 SQL Server 實例名稱的開始處添加 tc