Lỗi cannot connect sql server management studio 2023

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SQL Server Management Studio (SSMS) setup failed or requires restart

• Article
• 03/03/2023

In this article

When facing SSMS installation problems, common error messages include:

• "Failed to install MSI package"
• "Microsoft ODBC Driver 17 for SQL Server: A previous installation required a reboot of the machine for changes to take effect."
• "Fatal error during installation (0x80070643)"

Suggested resolution

Following these steps to uninstall the "Microsoft ODBC Driver 17 for SQL Server" before beginning the SSMS installation commonly allows the setup to succeed if it has previously failed with one of the above or similar error messages.

Vào một ngày, bạn mở MS SQL Server đăng nhập vào nhưng không được và nhận được cửa sổ thông báo (như sau):

Fix Error Can Not Login To SQL Server

Đây là lỗi máy chủ SQL Server của bạn chưa được bật. Mặc định thì sau khi cài đặt SQL Server sẽ khởi động cùng windows, nhưng vì lý do nào đó (có thể là do virut, hay do một ứng dụng nào đó đã tắt chức năng tự khởi động theo windows) nên lúc bạn khởi động lên mà máy chủ SQL server không khởi động thì đăng nhập sẽ gặp lỗi (như hình trên)

Để cách khắc phục lỗi này bạn có thể khởi động lại máy tính của mình một lần nữa có thể nó sẽ tự khởi động cùng windows. Tuy nhiên, về lâu về dài thì bạn cần bật dịch vụ (server sql server) khởi động cùng windows.

Bật SQL Server khởi động cùng windows như sau:

Bước 1: Mở cửa rổ RUN bằng cách nhấn tổ hợp phím: Window (biểu tượng cửa sổ) + R (cho các máy sử dụng HĐH Windows)

Nhập vào "services.msc" nhấn Enter một cửa sổ quản lý các Services của windows mở ra

Bước 2: Bạn tìm đến dòng SQL Server (SQLExpress) (Nhấn chữ S để duyệt tới cho nhanh). Trong đó SQLExpress là tên máy chủ của bạn (nếu đã thay đổi thì sẽ khác, mặc định là SQLExpress) của tôi là ITSQLEXPRESS (Xem hình dưới)

Tìm đến dòng SQL Server (SQLExpress)

Nhìn vào vùng khoanh đỏ bạn thấy services này chưa được Start và nó đang ở chế độ Manual (tức là không tự động khởi động (Automatic))

Bây giờ chỉ cần click chuột phải vào dòng đó rồi chọn Start là bạn có thể login vào được SQL rồi.

Để máy chủ SQL Server tự động khởi động cùng Windows mà không cần phải vào đây để Start lại thì bạn thì Click phải chuột vào dòng đó, chọn Properties tại phần Startup Type: Chọn Automatic, đồng thời nhấn Start rồi nhấn OK để hoàn thành.

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• Article
• 05/11/2023

In this article

Applies to: SQL Server

When connecting to a SQL Server instance, you may encounter one or more of the following . This article provides some steps to help you troubleshoot these errors, which are provided in order of the issues from simple to complex.

Error messages

The complete error messages vary depending on the client library that's used in the application and the server environment. You can check the following details to see if you're encountering one of the following error messages:

"A network-related or instance-specific error occurred while establishing a connection to SQL Server. Verify that the instance name is correct and that SQL Server is configured to allow remote connections"

provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server (Microsoft SQL Server, Error: 53) A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server (Microsoft SQL Server, Error: 53) provider: TCP Provider, error: 0 - No such host is known. (Microsoft SQL Server, Error: 11001) provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified Login timeout expired SQL Server Native Client Data Link Error [Microsoft SQL Server Native Client 10.0]: Login timeout expired [Microsoft SQL Server Native Client 10.0]: A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online. [Microsoft SQL Server Native Client 10.0]: SQL Server Network Interfaces: Error Locating Server/Instance Specified [xFFFFFFFF]. A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. provider: TCP Provider, error: 0 A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. Microsoft SQL Server, Error: 10060 provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server Microsoft SQL Server, Error: 53 The network path was not found [Microsoft][SQL Server Native Client 11.0]TCP Provider: No connection could be made because the target machine actively refused it SQL Server Native Client Data Link Error [Microsoft][SQL Server Native Client 11.0]TCP Provider: No connection could be made because the target machine actively refused it. [Microsoft][SQL Server Native Client 11.0]Login timeout expired. [Microsoft][SQL Server Native Client 11.0]A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow remote connections. For more information see SQL Server Books Online.

"SQL Server does not exist or access denied"

This error usually means that the client can't find the SQL Server instance. This issue occurs when at least one of the following problems exists:

• The name of the computer hosting SQL Server is incorrect.
• The instance doesn't resolve the correct IP.
• The TCP port number isn't specified correctly.

Windows error 233: No process is on the other end of the pipe

The complete message is:

A connection was successfully established with the server, but then an error occurred during the login process. (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe.) (Microsoft SQL Server, Error: 233)

This message means that SQL Server isn't listening on the Shared Memory or Named Pipes protocol.

Gather information for troubleshooting the error

We recommend that you gather the information listed in this section using one of the following options before proceeding with the actual steps to troubleshoot the error.

Option 1: Use the SQL Check tool to gather the required information

If you can sign in locally to the SQL Server computer and have administrator access, use SQLCheck from the Microsoft SQL Networking GitHub repository. This tool provides most of the information required for troubleshooting in one file. Review the tool's home page for more information on using the tool and the information it gathers. You can also check the recommended prerequisites and checklist page.

Option 2: Collect the data individually using the following procedures

Get the instance name from Configuration Manager

On the server that hosts the SQL Server instance, use SQL Server Configuration Manager to verify the instance name:

Note

Configuration Manager is automatically installed on the computer when SQL Server is installed. Instructions on starting Configuration Manager vary slightly by versions of SQL Server and Windows. For version-specific details, see SQL Server Configuration Manager.

1. Sign in to the computer hosting the instance of SQL Server.
2. Start SQL Server Configuration Manager.
3. In the left pane, select SQL Server Services.
4. In the right pane, verify the name of the instance of the database engine.
   • SQL SERVER (MSSQLSERVER) indicates a default instance of SQL Server. The name of the default instance is .
   • SQL SERVER () indicates a named instance of SQL Server. The name of the named instance is \.

Get the IP address of the server

You can use the following steps to get the IP address of the computer hosting the instance of SQL Server.

1. On the Start menu, select Run. In the Run window, type cmd, and then select OK.
2. In the Command Prompt window, type ipconfig/all and then press Enter. Note down the IPv4 address and the IPv6 address. Note SQL Server can connect by using either IP version 4 protocol or IP version 6 protocol. Your network could allow either or both.

Get the TCP port of the instance

In most cases, you connect to the Database Engine on another computer by using the TCP protocol. To get the TCP port of the instance, follow these steps:

1. Use SQL Server Management Studio on the computer running SQL Server and connect to the instance of SQL Server. In Object Explorer, expand Management, expand SQL Server Logs, and then double-click the current log.
2. In the Log File Viewer, select Filter on the toolbar. In the Message contains text box, type server is listening on, select Apply filter, and then select OK.
3. A message like "Server is listening on [ 'any' 1433]" should be listed.

   This message indicates that the instance of SQL Server is listening on all IP addresses on this computer (for IP version 4) and TCP port 1433. (TCP port 1433 is usually the port that's used by the Database Engine or the default instance of SQL Server. Only one instance of SQL Server can use this port. If more than one instance of SQL Server is installed, some instances must use other port numbers.) Note down the port number used by the SQL Server instance that you're trying to connect to. Note

   • IP address 127.0.0.1 is probably listed. It's called the loopback adapter address. Only processes on the same computer can use the IP address to connect.
   • You can also view the SQL Server error log by using a text editor. By default, the error log is located at Program Files\Microsoft SQL Server\MSSQL.n\MSSQL\LOG\ERRORLOG and ERRORLOG.n files. For more information, see Viewing the SQL Server error log.

Step 1：Verify that the instance is running

Option 1: Use the output file from the SQLCheck tool

1. Search the output from SQLCheck file for "SQL Server Information".
2. In the section titled "Services of Interest", find your SQL Server instance under Name and Instance (for named instances) columns and check its status by using Started column. If the value is True, the services are started. Otherwise the service is currently not running.
3. If the service isn't running, start the service by using either SQL Server management studio, SQL Server Configuration manager, PowerShell, or Services applet.

Option 2: Use SQL Server Configuration Manager

To verify that the instance is running, select SQL Server Services in SQL Server Configuration Manager and check the symbol by the SQL Server instance.

• A green arrow indicates that an instance is running.
• A red square indicates that an instance is stopped.

If the instance is stopped, right-click the instance and select Start. Then, the server instance starts, and the indicator becomes a green arrow.

Option 3: Use PowerShell commands

You can use the following command in PowerShell to check the status of SQL Server services on the system:

Get-Service | Where {$_.status -eq 'running' -and $_.DisplayName -like "sql server*"}

You can use the following command to search the error log file for the specific string "SQL Server is now ready for client connections. This is an informational message; no user action is required.":

Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

Step 2: Verify that the SQL Server Browser service is running

Note

This step is required only for troubleshooting connectivity issues with named instances.

Option 1: Use the output file from SQLCheck tool

1. Search the output from SQLCheck file for "SQL Server Information".
2. In the section titled "Services of Interest", search for SQLBrowser in the Name column and check its status using the Started column. If the value is True, the service is started. Otherwise, the service is currently not running, and you need to start it. For more information, see Start, stop, pause, resume, restart SQL Server services.

Option 2: Use SQL Server Configuration Manager

To connect to a named instance, the SQL Server Browser service must be running. In SQL Server Configuration Manager, locate the SQL Server Browser service and verify that it's running. If it's not running, start the service. The SQL Server Browser service isn't required for default instances.

For more information on using SQL Server Browser service in your environment, see SQL Server Browser service.

For more information on stopping and starting SQL Services, see Start, stop, pause, resume, restart SQL Server services.

Step 3: Verify the server name in the connection string

You often encounter errors when an incorrect server name is specified in the connection string. Make sure that the server name matches the one that you retrieved in the previous steps.

Note

If you are using the SQLCheck tool, review the NetBios Name/FQDN values in the Computer Information section of the output file.

• For examples on connection strings, see SQL Server Connection Strings.
• For more detailed examples, see Proof of concept connecting to SQL using ADO.NET under Homepage for SQL client programming.

Step 4: Verify the aliases on the client machines

Aliases are often used in client environments when you connect to SQL Server with an alternate name or when there are name resolution issues in the network. They're created by using SQL Server Configuration Manager or client network utility. An incorrect alias can cause the connections from your applications to connect to the wrong server, resulting in failure. Use the following methods to check for incorrect aliases. You can also use a tool (such as SQLCHECK) on the client machine to check for aliases and various other connectivity-related settings on a client machine.

Option 1: Use the output file from the SQLCheck tool

1. In the SQLCheck output file, search for the string SQL Aliases. (This string will be inside the Client Security and Driver Information section of the file)
2. Review the entries in the table. If there's none present, there are no aliases on the computer. If there's an entry, review the information to ensure the server name and port number are set to the correct values.

Example output: SQL Aliases:

Alias Name   Protocol   Server Name     Port   32-bit 

prodsql      TCP        prod_sqlserver  1430      

The output indicates that prodsql is an alias for a SQL Server called prod_sqlserver that's running on port 1430.

Option 2: Check aliases in SQL Server Configuration Manager

1. In SQL Server Configuration Manager, expand SQL Server Native Client Configuration, and select Aliases.
2. Check whether any aliases are defined for the server that you're trying to connect to.

   If the aliases exist, follow these steps:

   1. Open the Properties pane of the alias.
   2. Rename the value in the Alias Name field (for example, if your server name is MySQL, rename it as MySQL_test) and retry the connection. If the connection works, your alias is incorrect and may come from an old configuration that is no longer needed. If the connection doesn't work, rename the alias back to its original name and go to the next step.
   3. Check the connection parameters for the alias and make sure that they're correct. The following common scenarios can cause connectivity problems:
      • Incorrect IP address for the Server field. Make sure that the IP address matches the entry in the SQL Server error log file.
      • Incorrect server name in the Server field. For example, your server alias points to the correct server name. However, the connections will fail if the value of the server name parameter is incorrect.
      • Incorrect pipe name format (assuming that you use a named pipes alias).
        • When connecting to a default instance named Mydefaultinstance, the pipe name should be \\Mydefaultinstance\pipe\sql\query.
        • When connecting to a named instance MySQL\Named, the pipe name should be \\MySQL\pipe\MSSQL$Named\sql\query.

Option 3: Check aliases in SQL Server Client Network Utility

1. Open SQL Server Client Network Utility by typing cliconfg.exe in your Run command.
2. Follow step 2 in .

Step 5: Verify the firewall configuration

You can verify the firewall configuration depending on the default instance or named instance.

Note

If you are using third party firewalls in your network, the concepts still apply. However, you may have to work with your network administrator or consult the firewall product's documentation for more information on configuring the firewall to allow necessary ports for communication with SQL Server.

Default instance of SQL Server

A default instance typically runs on port 1433. Some installations also use a non-standard port (other than 1433) to run SQL instances. The firewall may block either port. To check the port number further, follow these steps:

1. Determine the port your SQL instance is running on, see .
2. * If your SQL Server is configured to listen on port 1433, make sure that firewalls on the network between the client and the server allow traffic on that port. Review Configure a Windows Firewall for Database Engine Access and work with your network administrator to implement necessary solutions.
   • If your SQL Server default instance isn't using 1433, try to append the port number of SQL Server to the server name by using the format , and see whether it works. For example, your SQL instance name is MySQLDefaultinstance and it's running on port 2000. Specify the server name as MySQLServer, 2000 and see whether it works.
     • If it doesn't work, it indicates the firewall is blocking the port. You can follow the instructions at Configure a Windows Firewall for Database Engine Access or work with your network administrator to add the port to the firewall exclusion list.
     • If it does work, it indicates that the firewall is allowing communication through that port. You need to change your connection string in order to use the port number and your server name in the connection string of your application.

Named instance of SQL Server

If your SQL instance is a named instance, it may be configured to use either dynamic ports or a static port. In either case, the underlying network libraries query the SQL Server Browser service running on your SQL Server machine through UDP port 1434 to enumerate the port number for the named instance. If a firewall between the client and the server blocks this UDP port, the client library can't determine the port (a requirement for connection) and the connection fails. To check the connection, you can use one of the following methods:

• Method 1: Check connection by specifying the port number in your connection string.
  1. Determine the port your SQL instance is running on, see .
  2. Try to connect to the named instance by using the port number appended to the server name in the format , and see if that works. For example, if your SQL instance name is MySQL\Namedinstance and it's running on port 3000, specify the server name as MySQL\Namedinstance,3000.
     • If it does work, it indicates the firewall is blocking the UDP port 1434 or the instance is hidden from SQL Server Browser.
     • If it doesn't work, it indicates one of the following situations:
       • Either UDP port 1434 is blocked or the static port is blocked, or both. To confirm whether it's the UDP port or the static port, use Portqry.
       • The instance is hidden from the SQL Server Browser service.
• Method 2: Check the connection by using the PortQryUI tool.

  Use the PortQryUI tool with your named instance and observe the resulting output. You may see a message that the UDP port 1434 is filtered. This message indicates that the port is blocked on the network. For instructions on how to use the tool, see Using the PortQryUI Tool with SQL Server. Determine whether the SQL Server instance is listening on dynamic or static ports. Then use the following method that is relevant to your scenario. If you aren't sure, see How to check if SQL Server is listening on a dynamic port or static port.

  • Scenario 1: Dynamic ports. In this case, ensure that the SQL Server Browser service is started and UDP port 1434 isn't blocked on the firewall between the client and the server. If you can't do either of these things, you should switch your SQL Server instance to a static port and use the procedure documented in Configure a Server to Listen on a Specific TCP Port.
  • Scenario 2: Static port configuration. Either SQL Server Browser isn't running or UDP 1434 can't be opened on the firewall. In this case, make sure to specify the static port in your connection string and that the firewall doesn't block the port. For more information, review Configure a Windows Firewall for Database Engine Access.

Step 6: Verify the enabled protocols on SQL Server

In some installations of SQL Server, connections to the Database Engine from another computer aren't enabled unless an administrator manually enables them. You can use one of the following options to check and enable the necessary protocols to allow remote connections to SQL Server Database Engine.

Option 1: Use the output file from SQLCheck tool

1. Search the SQLCheck output file for "Details for SQL Server instance" section and locate the information section for your SQL Server instance.
2. In the section, find the values listed in the following table to determine if the SQL Server protocols are enabled: Value name Implication More information Shared Memory Enabled Can either be true of false - only affects local connections. Creating a Valid Connection String Using Shared Memory Protocol Named Pipes Enabled If false, both local and remote connections using Named pipes will fail Choosing a Network Protocol TCP Enabled If false, both local and remote connections using TCP/IP will fail. Note The majority of the SQL Server installations use TCP/IP as the communication protocol between server and the client. Choosing a Network Protocol
3. Enable required protocols by using SQL Server Configuration Manager or SQL Server PowerShell. For more information, see Enable or Disable a Server Network Protocol. Note After enabling a protocol, the Database Engine must be stopped and restarted for the change to take effect.

Option 2: Use SQL Server Configuration Manager

To enable connections from another computer by using the SQL Server Configuration Manager, follow these steps:

1. Open the SQL Server Configuration Manager.
2. In the left pane, expand SQL Server Network Configuration, and then select the instance of SQL Server that you want to connect to. The right pane lists the connection protocols available. Shared Memory is normally enabled. It can only be used from the same computer, so most installations leave Shared Memory enabled. To connect to SQL Server from another computer, use TCP/IP. If TCP/IP isn't enabled, right-click TCP/IP, and then select Enable.
3. If you change the enabled setting for any protocol, restart the Database Engine. In the left pane, select SQL Server Services. In the right-pane, right-click the instance of the Database Engine, and then select Restart.

Step 7: Test TCP/IP connectivity

Connecting to SQL Server by using TCP/IP requires that Windows establish the connection. You can use the following steps to test TCP connectivity by using the ping tool.

1. On the Start menu, select Run. In the Run window, type cmd and select OK.
2. In the Command Prompt window, type ping and the IP address of the computer that's running SQL Server. For example:
   • IPv4: ping 192.168.1.101
   • IPv6: ping fe80::d51d:5ab5:6f09:8f48%11
3. If your network is configured properly, ping returns

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   1 followed by some additional information. If ping returns

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   3 or

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   4, TCP/IP isn't correctly configured. Errors at this point indicate a problem with the client computer, the server computer, or something about the network such as a router. To troubleshoot network problems, see Advanced troubleshooting for TCP/IP issues.
4. If the ping test succeeds by using the IP address, test whether the computer name can be resolved to the TCP/IP address. On the client computer, in the Command Prompt window, type ping and the name of the computer that's running SQL Server. For example,

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   6.
5. If ping to the IP address succeeds, but ping to the computer name returns

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   3 or

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   4, you might have old (stale) name resolution information cached on the client computer. Type

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   9 to clear the DNS (Dynamic Name Resolution) cache. Then ping the computer by name again. When the DNS cache is empty, the client computer checks the latest information about the IP address for the server computer.
6. If your network is configured properly, ping returns

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   1 followed by some additional information. If you can successfully ping the server computer by IP address but receive an error such as

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   3 or

   Get-ChildItem -Path "c:\program files\microsoft sql server\mssql*" -Recurse -Include Errorlog | Select-String "SQL Server is now ready for client connections."

   4 when pinging by computer name, then name resolution isn't correctly configured. For more information, see how to Troubleshoot Basic TCP/IP Problems. Successful name resolution isn't required to connect to SQL Server. However, if the computer name can't be resolved to an IP address, connections must be made to specify the IP address. Name resolution can be fixed later.

Step 8: Test local connection

Before troubleshooting a connection problem from another computer, test your ability to connect from a client application installed locally on the computer that is running SQL Server. Local connection avoids issues with networks and firewalls.

This procedure requires SQL Server Management Studio. If you don't have Management Studio installed, see Download SQL Server Management Studio (SSMS).

If you can't install Management Studio, you can test the connection by using the sqlcmd.exe utility. sqlcmd.exe is installed with the Database Engine. For information about sqlcmd.exe, see sqlcmd Utility.

1. Sign in to the computer where SQL Server is installed by using a login that can access SQL Server. During installation, SQL Server requires at least one login to be specified as a SQL Server administrator. If you don't know an administrator, see Connect to SQL Server When System Administrators Are Locked Out.
2. On the Start page, type SQL Server Management Studio, or on the Start menu of the older versions of Windows, select All Programs, select Microsoft SQL Server, and then select SQL Server Management Studio.
3. On the Connect drop-down menu, select Database Engine. In the Authentication box, select Windows Authentication. In the Server name box, type one of the following connection types:

   Connecting to Type Example Default instance

   `

   Alias Name Protocol Server Name Port 32-bit

   ---

   prodsql TCP prod_sqlserver 1430

   4

   Alias Name Protocol Server Name Port 32-bit

   ---

   prodsql TCP prod_sqlserver 1430

   5 Named Instance

   Alias Name Protocol Server Name Port 32-bit

   ---

   prodsql TCP prod_sqlserver 1430

   6

   Alias Name Protocol Server Name Port 32-bit

   ---

   prodsql TCP prod_sqlserver 1430

   ` 7 Note When connecting to SQL Server from a client application on the same computer, the shared memory protocol is used. Shared memory is a type of local named pipe, so you sometimes encounter errors related to pipes.
4. If you receive an error at this point, you must resolve it before proceeding. Your login might not be authorized to connect. Your default database might be missing. Note You can't troubleshoot the problem without enough information because some error messages are passed to the client intentionally. This is a security feature to avoid providing an attacker with information about SQL Server. To view the details about the error, see the SQL Server error log.
5. If you receive error 18456 Login failed for user, Books Online article MSSQLSERVER_18456 contains additional information about error codes. Aaron Bertrand's blog also has an extensive list of error codes at Troubleshooting Error 18456 (external link). You can view the error log by using SSMS (if you can connect), in the Management section of the Object Explorer. Otherwise, you can view the error log with the Windows Notepad program. The default location varies with your version and can be changed during setup. The default location for SQL Server 2019 (15.x) is C:\Program Files\Microsoft SQL Server\MSSQL15.MSSQLSERVER\MSSQL\Log\ERRORLOG.
6. If you can connect by using shared memory, test connecting by using TCP. You can force a TCP connection by specifying `

   Alias Name Protocol Server Name Port 32-bit

   ---

   prodsql TCP prod_sqlserver 1430

   8 before the name. Here are the examples: Connecting to: Type: Example: Default instance

   Alias Name Protocol Server Name Port 32-bit

   ---

   prodsql TCP prod_sqlserver 1430

   ` 9`prodsql`0 Named Instance`prodsql`1`prodsql`2
7. If you can connect by using shared memory but not TCP, you must fix the TCP problem. The most likely issue is that TCP isn't enabled. To enable TCP, see .
8. If your goal is to connect by using an account other than an administrator account, you can begin by connecting as an administrator. Then, try to connect again with the Windows Authentication login or the SQL Server Authentication login that the client application uses.

Step 9: Test remote connection

Once you can connect by using TCP on the same computer, it's time to try to connect from the client computer. You could use any client application, but to avoid complexity, install the SQL Server Management tools on the client. After installation, try to use SQL Server Management Studio.