SQL Server Recovery

“SQL Server Login Failed Error 233” is Easy to Fix Using These Solutions

Stacy Brown ~ Modified: April 10th, 2023 ~ SQL Master Database ~ 5 Minutes Reading

SQL Server Login Failed Error 233

While accessing the DB sometimes user faces the situation when they logging into SQL Server Authentication mode, and it displaying the error message as shown below. Moreover, users also face several errors other than SQL server error 233 like Error 26. Error 40, Error 3271, etc. This is called SQL Server Login Failed Error 233 :

Table of Content

SQL Server Error 233

Fix SQL Server Error 233 in 6 Quick Steps

  • Enable TCP/IP in SQL configuration manager.
  • Now, Enable the Shared Memory Protocol.
  • At this step, Enable Named Pipes Protocol.
  • Enable the (VIA) Virtual Interface Adapter.
  • Add Correct Port in Windows Firewall.
  • Simply Allow the Remote Connections.

SQL Server Login Failed Error 233 – Walkaround

We can overcome the issue faced by users while authenticating the SQL Server through common fixes. There are some of the possible ways, which helps user to resolve the SQL server error 233 by checking and enabling the following settings in SQL Configuration Manager as discussed below:


There are two or more SQL Servers, which are associated across network. Then, all the communication is done by using TCP/IP protocol. There is a default port for SQL Server Installation, i.e. 1433. This port can be changed if required through SQL Server Configuration Manager. For SQL Server to be connected properly, TCP/IP should be enabled. Follow the steps given below to solve Microsoft SQL server error 233 safely.

  1. Open MS SQL Server in your system
  2. Go to configuration tools, and then open SQL Server Configuration Manager in your system >> SQL Server Network Configuration.
  3. Choose TCP/IP option and enable it with a right-click

After completing the procedure, restart the SQL Server for the changes to take place.

2. Shared Memory Protocol

The Shared Memory Protocol is used for connecting SQL Server, which is running on the same system. It is not useful for most of the database activity. Sometimes, the user faces an authentication error, when Shared Memory protocol is disabled. It can be easily enabled with the few possible steps as discussed:

  1. Go to StartAll ProgramsMS SQL ServerConfiguration ToolsSQL Server Configuration Manager.
  2. Choose SQL Server Network Configuration.
  3. Then, right-click on the option Shared Memory → Choose Enable.

3. Named Pipes Protocol

Named Pipes protocols are established for local area networks. In it, a part of memory is used by one procedure to pass the info to other process. Another way can be on the same system or on a networked system. User faces this SQL server error 233 because the Named Pipes are disabled, so to enable it user can follow the same procedure as mentioned above by opening the SQL Server Configuration ManagerSQL Server Network Configuration Named Pipes ProtocolEnable.

4. Virtual Interface Adapter

VIA is Virtual Interface Adapter, which works with VIA hardware. Even, the user faces an error when VIA is not enable in your system. So, to remove the Microsoft SQL server error 233 issue, enable the VIA option from the SQL Server Network configuration.

5. View Port in Windows Firewall

Windows Firewall acts like a wall in between the server and your system, to protect from all malicious attacks. However, various ports and services are refrained by default from firewall. Even SQL Server ports are not viewed in firewall.

SQL Server ports are running on the system, are added to exception, and then firewall filters all traffic from those ports. SQL Server runs on 1433 port by default but if the default port is changed, then the new port is added to the exception. It can be done following the step:

  1. First, open Control Panel in your system.
  2. Now select Windows Firewall → Change Settings.
  3. Click on Exceptions, and then select Add Port.
  4. A window will appear, now fill the port number, and click on Ok button.
  5. Then, enable the SQL.

6. Check for Remote Connection

To enable the remote connection is also important. If this feature is turned off, then SQL Server will work properly on your system but if your feature is on then, follow the steps given below & get rid of SQL server error 233 smartly:

  1. Click on Server node → choose Properties.
  2. At left Tab select connection → check the option “allow remote connections to this server”


In the above discussion, there are some relevant solutions discussed to remove the SQL Server Authentication Error 233. If the user still faces an error, then they can utilize an alternate method, i.e. use sqlbrowser.exe. It is another way to prevent the occurrence of this error by simply searching sqlbrowser.exe on the drive where SQL Server is installed. Then, copy the path of sqlbrowser.exe and create an exception of that file on Firewall. It helps to resolve the SQL login failed error 233.

Also Read: SQL Server Does Not Exist or Access Denied – Best Solution


Q-1. What is error 233 in SQL Server?

Ans. SQL Server error 233 occurs when the client is unable to connect to their SQL Server. It occurs due to several reasons but mainly when remote connections aren’t allowed.

Q-2. How to enable TCP/IP in SQL Server?

Ans. Follow the simple steps to enable TCP/IP:

  • Open the SQL Configuration Manager.
  • Select SQL Server Network Configuration
  • Select Protocol option
  • Enable TCP IP protocol.

Q-3. How to configure SQL Server to accept remote connections?

Ans. Open SQL Server Management Studio & follow these steps:

  • Open Object Explorer.
  • Right Click Server & Select Properties.
  • Choose the Connections Mode.
  • Go to Remote server connections.
  • Select Allow Remote Connections.

Q-4. How do I open port 1433 in SQL Server?

Ans. Evidenty, Connect SQL Server & Open Windows Firewall. Click Inbound Rules & Select the New Rules option. Select Port Type & Rules & then Specify 1433 and 1434 ports.