Why am I getting Cannot Connect to Server - A network-related or instance-specific error

Question

I get the following error when trying to connect to SQL Server   Cannot connect to 108 163 224 173  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  1326   This error is thrown when I try to configure my database to gridview in Visual Studio 2010  I m at a loss as to how to debug this error  How would you debug this error   What steps should I take in order to determine what is really going on here  in addition to the one mentioned in the error message

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Why this error is so boresome and noisy  just because it can occur in varied situation  I have done all approchs above here  and still being sucked  So make sure u have done the same as me before browsing downward  Maybe I am not able to fix ur situation instantly  but I can point out a direction or thinking to u The one who finally slide down here    I have started to ponder the error of  my running program occurring after I made sure that the instance name is clearly right and set my database to allow remote control following the methods above  After then  I suspected something wrong happening in my code snippet of SQL connection  Solution of my problem   Check my sqlconnection function    Click to see its configuration    New a connection    Select ur server name   It works for me with pondering what exactly happen in the process of connection Hope my thinking will lead u to kill ur error

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You can test the following methods         a         Check the connection string of the project       b         Go to services and restart SQLServer Instance       c         Open  SQLServer  Configuration Manager    In the left panel select  SQLServer Network Configuration  and expanding it   Select  Protocols for MSSQLServer    In the right panel dbl click on  TCP IP    In the  Protocol  tab set the  Enabled  to  Yes    In the  IP Addresses  tab scroll to down   In the  IPAll  set  TCP Port  to 1433      d         Open  Firewall with advanced security    In the right tab select  Inbound Rules          In the middle tab find the record that  local Port  is 1433  If you can t found it try to created it with following levels   In the Start menu  click Run  type  WF msc   and then click OK In the left panel click the  Windows Firewall with Advanced Security  In the right panel right-click  Inbound Rules   and then click  New Rule  In the Rule Type dialog box  select  Port   and then click Next In the Protocol and Ports dialog box  select  TCP   and select  Specific Local Ports   and then type the port number 1433  Click Next In the Action dialog box  select Allow the connection  and then click Next In the  Profile  dialog box  checking the Domain  Private and Public  Then click Next In the  Name  dialog box  type  SQL 1433 Port  and for a description write description for own  Then click Finish         Then in the middle tab double click the found item Instance  or created item of   SQL 1433 Port  name by you    Select  Scope  tab in opened dialog box SQL Server Properties    In the Local PC Go to google com in your Browser and search  My IP     then copy of your  IP     Go to the remote server and in the  SQL Server Properties  dialog box of  Scope  tab  in the  Remote IP Address  select the  These IP Addresses  option and click  Add  button   In the opened dialog box IP Address  select  This IP Address or Subnet  option and paste your  IP   click OK button

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When I experienced this error in Visual Studio          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          it was during the execution of the following C  code  which was attempting to obtain my SQL Server data to display it in a grid  The break occurred exactly on the line that says connect Open             using  var connect   Connections mySqlConnection                        const string query    SELECT Name  Birthdate  Narrative FROM Friends               using  var command   new SqlCommand query  connect                                 connect Open                    using  var dr   command ExecuteReader                                          while  dr Read                                                     blah                                                                   It was inexplicable because the SQL query was very simple  I had the right connection string  and the database server was available  I decided to run the actual SQL query manually myself in SQL Management Studio and it ran just fine and yielded several records  But one thing stood out in the query results  there was some improperly encoded HTML text inside a varchar max  type field within the Friends table  specifically  some encoded comment symbols of the sort  lt  -- lodged within the  Narrative  column s data   The suspect data row looked like this   Name    Birthdate    Narrative                                      Fred    21-Oct-79     amp lt  --HTML Comment -- gt Once upon a time      Notice the encoded HTML symbol   amp lt    which stood for a   lt   character  Somehow that made its way into the database and my C  code could not pick it up  It failed everytime right at the connect Open   line  After I manually edited that one row of data in the database table Friends and put in the decoded   lt   character instead  everything worked  Here s what that row should have looked like   Name    Birthdate    Narrative                                      Fred    21-Oct-79     lt  --HTML Comment -- gt Once upon a time      I edited the one bad row I had by using this simple UPDATE statement below  But if you had several offending rows of encoded HTML  you might need a more elaborate UPDATE statement that uses the REPLACE function   UPDATE Friends SET Narrative     lt  --HTML Comment -- gt Once upon a time     WHERE Narrative LIKE   amp lt     So  the moral of the story is  at least in my case   sanitize your HTML content before storing it in the database and you won t get this cryptic SQL Server error in the first place   Uh  properly sanitizing decoding your HTML content is the subject of another discussion worthy of a separate StackOverflow search if you need more information

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I have to run SQL Server Browser service into SQL Server Configuration Manager   Installation can t discover newly created service without this

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I have tried almost everything  Then  I have uninstalled Malwarebytes  A software which claims that it can remove malware  often it can   After that  all is fine  Maybe somebody might run into the same issue for the same reason

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In case you might be using the Express Edition   Add   SQLEXPRESS  after your server name  e g   MY-SERVER SQLEXPRESS

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My issue was that you need to have a connection string entry in both your repository layer and web layer  Once I added it to my web config as well as my app config  Entity Framework was able to create the migration   My question is why  does the web config need it  when there is absolutely no database access there

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I also had this issue  I tried everything which suggested in this post but nothing worked  Finally I solved my issue by executing this query in my SQL Server  EXEC sp configure  remote access   0     GO   RECONFIGURE     GO

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Along with trying everything as suggested by Teo Chuen Wei Bryan  make sure you are also referring to the correct Server Instance name in the connection string    If you are using the short form of host name Instance on the database server or in the web config file  make sure you use the fully qualified domain name FQDN  Instance  Also  to test connectivity from a server where SQL server client is NOT present    --  create a text file and change its file extension to  udl  --  Right click the file and you can see connection tab    --  Input server name and log on information to test connection to the database server    Hope this helps

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I found the following techniques helpful       Make sure your database engine is configured to accept remote connections          Start   All Programs   SQL Server 2005   Configuration Tools   SQL Server Surface Area Configuration   Click on Surface Area Configuration for Services and Connections   Select the instance that is having a problem   Database Engine   Remote Connections   Enable local and remote connections   Restart instance        You may need to create an exception on the firewall for the SQL Server instance and port you are using          Start   Run   Firewall cpl   Click on exceptions tab    Add sqlservr exe  typically located in C  Program Files  x86  Microsoft SQL Server MSSQL x MSSQL Bin  check your installs for the actual folder path  and port  default is 1433    Check your connection string as well       From FIX   ERROR   Could not open a connection to SQL Server      Check if your SQL server services is up and running properly          Go to All Programs   Microsoft SQL Server 2008   Configuration Tools   SQL Server Configuration Manager   SQL Server Services   Check to make sure SQL Server service status is Running          In addition  ensure that your remote server is in the same network  Run sqlcmd -L to ascertain if your server is included in your network list      Enable TCP IP in SQL Server Configuration      When two or more SQL Servers are connected across network they do all communication using TCP IP  The default port of SQL Server installation is 1433  This port can be changed through SQL Server Configuration Manager  TCP IP should be enabled for SQL Server to be connected          Go to All Programs    Microsoft SQL Server 2008    Configuration Tools    SQL Server Configuration Manager    Select TCP IP   Right Click on TCP IP    Click on Enable         You must restart SQL Server Services for all the changes to take effect  Right click and go to menu properties to select location where default port of SQL Server can be changed

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I know this is buried  but I had caused this issue when I moved a database without giving the NT Service MSQLSERVER account rights to the directory I moved the database files to   Giving the rights and restarting SQLServer did the trick

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In my situation MSSQLSERVER service had a problem so I restarted the service and problem solved   So I recommend to go to Services app by   Windows key  search  Services   then find your Sql instance usually  SQL Server  MSSQLSERVER   at for Microsoft sql server  Right click on service and click on Start  if disabled click on Restart

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Adding my heavily upvoted comment as an answer with screenshots   I spent a lot of time on this  finally what worked for me is    1  Open Sql Server Configuration Manager --  SQL Server Network configuration --  Protocols for  lt  INSTANCE   --  TCP IP  double click on it      2  Select --  IP Addresses Tab     3  Go to the last entry IP All and mention TCP Port 1433      4  Press Win R and enter services msc   5  Now restart SQL Server  lt  INSTANCE        After this  the problem got resolved

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Just restart SQL Server  MSSQLSERVER  service

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I encountered the same problem In my case  I solved the problem in this way Step 1  From start menu went to SQL server configuration manager Step 2  Enabled TCP IP  Step 3  Double clicked TCP IP and went to IP Address last entry IP ALL and entered TCP Port 1433 then applied  Step 4   then pressed  win r  and wrote services msc opened the Services then scrolled down then right clicked on SQL Server  MSSQLSERVER  choose restart  That resolved my problem  Even if doing all of the above steps do not solve the problem then simply restart the PC then hopefully it will work

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It could also be as simple as the fact that your database is not actually MS SQL Server  If your database is actually MySql  for instance  and you try to connect to it with System Data SqlClient you will get this error   By far most examples of ADO Net will be for MSSQL and the inexperienced user may not know that you can t use SqlConnection  SqlCommand  etc   with MySql    While all ADO Net data providers conform to the same interface  you have to use the provider made for your database

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If you re encountering this while debugging in Visual Studio  make sure that the project build path points to a local drive  or follow these steps to grant permissions to the network folder

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I was experiencing the same problem and the problem was that I hade several projects in the solution  Weband Droid  and even though Default project was choosen in the Package Manager Console it used the connection string from the Droid project   PM gt  update-database -Verbose Using StartUp project  Droid    lt -- DROID Using NuGet project  Web    lt -- WEB Specify the  -Verbose  flag to view the SQL statements being applied to the target database   lt  -- BAD TARGET DATABASE -- gt  Target database is   DefaultConnection   DataSource    SQLEXPRESS  Provider  System Data SqlClient  Origin  Convention   System Data SqlClient SqlException  0x80131904   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      REMOVED TEXT  ClientConnectionId 00000000-0000-0000-0000-000000000000 Error Number -1 State 0 Class 20 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    After setting the Startup Project to Web and the Default Project in Package Manger Console I got it to work

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This Error mainly came when the SQL Service is stopped You need to Restart the service To go to this window you have to search the Services like this-   Then Search for SQLSERVER MSSQLSERVER  and Restart the service     Hope this will work

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If none of the above solutions work  nothing worked for me  then just RESTART your computer and you will be able to connect to your sql server  localhost

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Press window   R  Run window Open  and in run window type  services msc  and new services open find SQL SERVER with instance name in my case it s SQL SERVER SQLEXPRESS  then start this service and try again it works for me Hope Its Works for You also

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I got Solution for me       Open  SQL Server Configuration Manager       Now Click on  SQL Server Network Configuration  and Click on  Protocols for Name       Right Click on  TCP IP   make sure it is Enabled  Click on Properties      Now Select  IP Addresses  Tab -and- Go to the last entry  IP All       Enter  TCP Port   1433       Now  Restart   SQL Server  Name   using  services msc   winKey   r    It Will Work

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Xml tag arrangement in Web config is important   First   lt configSections gt       lt  -- For more information on Entity Framework configuration  visit http   go microsoft com fwlink  LinkID 237468 -- gt       lt section name  entityFramework  type  System Data Entity Internal ConfigFile EntityFrameworkSection  EntityFramework  Version 6 0 0 0  Culture neutral  PublicKeyToken b77a5c561934e089  requirePermission  false    gt   lt  configSections gt    After   lt connectionStrings gt     lt add name  SqlConnectionString  connectionString  Data Source    Initial Catalog TestDB  Trusted Connection True   providerName  System Data SqlClient    gt   lt  connectionStrings gt

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If SQL Server is running and you still get an error  When SQL Server is opened  instead of the default server name which is displayed you should select the server name ending with  SQLEXPRESS under the Server name- gt  Browse for more- gt  Database engine option

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I tried all the other answers on this question and some if not all probably played a part in getting this working for me  but I still couldn t connect to the DB remotely  I was using a SQL Server on an Azure VM   I eventually remembered that the VM has endpoints that are controlled by the Azure account proxy  so I went on to the Azure Portal and added 1433 as an available endpoint and I could connect to my SQL instance   Hope this helps someone who has tried all the other answers and is still having no luck

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I had the same error when I wanted to run my WinForms project  that includes working with a SQL Server database and that worked perfectly on my PC  on another PC  The problem was in Windows Firewall on my PC  I solved this by adding two rules  This is the whole procedure how to allow SQL Server through Windows Firewall    Open  Run  and enter services msc Find the service for SQL Server  instance name  and SQL Server Browser  One at a time  right click  select  Properties   copy the path to exe file   Then open firewall cpl  click allow an application or add rule  add the previously copied path  there is a procedure you need to follow   check Domain and Private  uncheck Public    This is the YouTube link where you can see this procedure  Allow SQL Server through Windows Firewall

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Try adding a   and a port number  as in  1433  to the end of your connection string

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I resolved this problem by setting the project that makes use of Entity Framework as the start-up project and then run the  update-database  command

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While the above solutions should work in 90  of the cases  but if you are still reading this answer    You are probably trying to connect to a different server than intended  It may be due to a configuration file pointing to a different SQL server than the actual server you think you are trying to connecting to   Happened to me atleast

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My issue started when I tried to change the server from IIS Express to Local IIS  while using LocalDB      I was using LocalDB  for dev purposes   and when I went to revert from Local IIS to IIS Express  Visual Studio had switched my data source from Data Source  LocalDb  MSSQLLocalDB to Data Source   SQLEXPRESS  Incorrect connection string   lt add name  DefaultConnection  connectionString  Data Source   SQLEXPRESS AttachDbFilename  DataDirectory  SurveyTestsDB mdf Initial Catalog SurveyTestsDB Integrated Security True User Instance True        providerName  System Data SqlClient    gt   Correct connection string   lt add name  DefaultConnection  connectionString  Data Source  LocalDb  MSSQLLocalDB AttachDbFilename  DataDirectory  SurveyTestsDB mdf Initial Catalog SurveyTestsDB Integrated Security True  providerName  System Data SqlClient    gt   Hope this helps someone out there

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Summary   To fix this issue encountered while running local app vs remote database  use SQL Server Configuration Manager to add an alias for the remote database   Details  I had run into this problem recently when transitioning from a Windows 7 to a Windows 10 laptop   I was running a local development and runtime environment accessing our Dev database on a remote server   We access the Dev database through a server alias setup through SQL Server Client Network Utility  cliconfg exe    After confirming that the alias was correctly setup in both the 64 and 32 bit versions of the utility and that the database server was accessible from the new laptop via SSMS  I still got the error seen by the OP  not the OP s IP address  of course    It was necessary to use SQL Server Configuration Manager to add an alias for the remote Dev database server   Fixed things right up

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I am using SQL Server 2016 and Window 10      First thing is to allow remote connection to SQL Server  What I did is to type sqlservermanager13 msc at start menu in order to open the SQL Server Configuration Manager  Make sure the TCP IP status is enabled    Check your TCP port number by double click TCP IP protocol name  Usually it is 1433 by default     The following procedures configure the Windows Firewall by using the Windows Firewall with Advanced Security Microsoft Management Console  MMC  snap-in  The Windows Firewall with Advanced Security only configures the current profile       To open a port in the Windows firewall for TCP access         On the Start menu  click Run  type WF msc  and then click OK    In the Windows Firewall with Advanced Security  in the left pane  right-click Inbound Rules  and then click New Rule in the action pane    In the Rule Type dialog box  select Port  and then click Next    In the Protocol and Ports dialog box  select TCP  Select Specific local ports  and then type the port number of the instance of the   Database Engine  such as 1433 for the default instance  Click Next    In the Action dialog box  select Allow the connection  and then click Next    In the Profile dialog box  select any profiles that describe the computer connection environment when you want to connect to the   Database Engine  and then click Next    In the Name dialog box  type a name and description for this rule  and then click Finish       Another thing to configure      To open access to SQL Server when using dynamic ports         On the Start menu  click Run  type WF msc  and then click OK    In the Windows Firewall with Advanced Security  in the left pane    right-click Inbound Rules  and then click New Rule in the action   pane    In the Rule Type dialog box  select Program  and then click Next    In the Program dialog box  select This program path  Click Browse    and navigate to the instance of SQL Server that you want to access   through the firewall  and then click Open  By default  SQL Server is   at C  Program Files Microsoft SQL   Server MSSQL13 MSSQLSERVER MSSQL Binn Sqlservr exe  Click Next    In the Action dialog box  select Allow the connection  and then   click Next    In the Profile dialog box  select any profiles that describe the   computer connection environment when you want to connect to the   Database Engine  and then click Next    In the Name dialog box  type a name and description for this rule    and then click Finish       Have a look at Microsoft doucmentation Configure a Windows Firewall for Database Engine Access

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I am solving that problem by opening Services then start running Sql Server  Sqlexpress  service

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Verify the account you are using to create a session for the SQL Server instance

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This error occurs when your sql server instance is stopped   GO to all Programs SQL Server  Configuration tools SQL SERVER CONFIGURATION MANAGER  then click on SQL sERVER SERVICES  list of instances will appear  select instance in question and click on play icon on top tool bar  hope this will help   this answer is very late but better late than never

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I moved from a work laptop on Windows 7 to a work laptop on Windows 10  I had been successfully using SSMS2016 on Windows 7   The same issue applied using SSMS2012 or SSMS2016  My access to the 10 sql servers using windows authentication was still the same   I could test this from another server  However  2 of the 10 servers would not connect from my laptop  Both were ms sql server 9 but I could connect to other sql server 9 databases   The solution was to add a firewall rule  using Windows Firewall with Advanced Security    Create an Incoming rule for each SSMS eg C  Program Files  x86  Microsoft SQL Server 130 Tools Binn ManagementStudio Ssms exe  I m not a network expert so I ve not included the details but hopefully it will point you in the right direction     Error msg  pre firewall rule   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    Net SqlClient Data Provider

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You may check service status of MS SQL Server 2014  In Windows 7 you can do that by    Go to search and Type  SQL Server 2014 Configuration Manager Then click on  SQL Server Service  on left menu  Check the instance of SQL Server service status if it is stopped or running If it has stopped  please change the status to running and log in to SQL Server Management Studio 2014

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After doing everything mentioned here  http   blog sqlauthority com 2009 05 21 sql-server-fix-error-provider-named-pipes-provider-error-40-could-not-open-a-connection-to-sql-server-microsoft-sql-server-error  Still did not work for me    Steps worked for me    Start  gt  Run  gt  cmd  gt  sqlcmd -L  It will prompt you the server name  Make sure this server name is same as the one you are trying to get connected to in CONNECT TO SERVER box of SQL management studio     I made this silly mistake I keep using MSSQLSERVER rather using this server name    Hope this helps for the people who make silly mistake like me    Thanks

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If you suddenly encounter this error say in a production environment and nothing has changed  try the following 4 items in the order below to see if it gets fixed    restart the sql server service  restart the service  say IIS  that is calling into sql server   the problem is probably here if the time between the start of the service call to SQL server and the time you end up getting the response error is super short  about one or two second   restart the server sql server is on  restart the server the calling service is on

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This solution solves both issues network error and the service behind SQL server  I answered a similar question here  you need to stat the other open Run type- gt  services msc - under services -  sort by stopped you will see a bunch of stopped SQL services Right click and start  To begin - there are 4 issues that could be causing the common LocalDb SqlExpress Sql Server connectivity errors SQL Network Interfaces  error  50 - Local Database Runtime error occurred  before you begin you need to rename the v11 or v12 to  localdb  mssqllocaldb    Troubleshooting Steps    You do not have the services running run this cmd  net start MSSQLSERVER or net start MSSQL  instancename You do not have the firewall ports here configured   Your install has and issue corrupt  the steps below help give you a nice clean start  You did not rename the V11 or 12 to mssqllocaldb SqlServer   I found that the simplest is to do the below - I have attached the pics and steps for help     Resolution Steps    First verify which instance you have installed  you can do this by checking the registry and by running cmd    cmd gt  Sqllocaldb exe i  cmd gt  Sqllocaldb exe s  whicheverVersionYouWantFromListBefore   if this step fails  you can delete with option d cmd  Sqllocaldb exe d  someDb  cmd gt  Sqllocaldb exe c  createSomeNewDbIfyouWantDb   cmd gt  Sqllocaldb exe start  createSomeNewDbIfyouWantDb

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It seems that your instance of localdb is not running  To start it on computer startup  add into your Start menu   Startup folder BAT file with following line  sqllocaldb start name of instance   where name of instance is name of localdb instance  which you want to start  You can list available instances in command line using sqllocaldb i   e g  If you re using SQL Server Management Studio and connecting to Server Name  localdb  v11 0  then your BAT file will look like  sqllocaldb start v11 0

[sql-server] Why am I getting "Cannot Connect to Server - A network-related or instance-specific error"?

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