SQL Network Interfaces error 26 - Error Locating Server Instance Specified

Question

Well i have a big problem that i m trying for days to solve but i could not do it  so i need your help  I have a web application in asp net 4 0 where i implemented custom membership and role providers  When i open the app homepage in it connects to the database and retrieves some information  There is also a login form and when i login it validates the user through the database and redirects me to the reserved pages but than this error appears      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    Description       An unhandled exception occurred during the execution of the current   web request  Please review the stack trace for more information about   the error and where it originated in the code    Exception Details       System Data SqlClient SqlException  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    Source Error       An unhandled exception was generated during the execution of the   current web request  Information regarding the origin and location of   the exception can be identified using the exception stack trace below    I tried many things  some solution i found in stackoverflow but nothing worked  Here are my connectionstrings    lt connectionStrings gt     lt clear  gt     lt remove name  LocalSqlServer   gt        lt add name  LocalSqlServer  connectionString  Data Source MSSQL2008-1 Initial Catalog agency          Integrated Security False User ID adis agency Password niarda2012 Connect Timeout 180 Encrypt False          Packet Size 4096  providerName  System Data SqlClient    gt        lt add name  AgencyConn  connectionString  Data Source MSSQL2008-1 Initial Catalog agency          Integrated Security False User ID adis agency Password niarda2012 Connect Timeout 180 Encrypt False          Packet Size 4096  providerName  System Data SqlClient   gt   lt  connectionStrings gt    Below are also the membership and role manager web config section    lt membership defaultProvider  AuthProvider  gt     lt providers gt       lt clear  gt         lt add name  AuthProvider  type  AuthenticationProvider  applicationName    Reserved   connectionStringName  AgencyConn   gt     lt  providers gt   lt  membership gt   lt roleManager enabled  true  defaultProvider  MyRoleProvider  gt     lt providers gt       lt clear  gt         lt add name  MyRoleProvider  type  RoleAccessProvider  connectionStringName  AgencyConn   gt     lt  providers gt   lt  roleManager gt    Please can anybody help to figure out whats wrong

User · Answer

Had the same issue then I used the connection string without     like DESKTOP-E53DUML instead of this   DESKTOP-E53DUML

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If you are using Developer Edition of SQL Server change    SQLEXPRESS  to your computer name in connection string   Before      Data Source   SQLEXPRESS Initial   Catalog SchoolDB-EF6CodeFirst Integrated   Security True MultipleActiveResultSets True   After      Data Source DESKTOP-DKV41G2 Initial   Catalog SchoolDB-EF6CodeFirst Integrated   Security True MultipleActiveResultSets True

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It turned out there were 2 versions of SQL Server installed on the machine  Removing the old one solved the issues on my side  More details  During the startup the services of both services were trying to run  And the one which was loaded first was working properly and was blocking the second to start  P S  Stopping the services of the first server and manually starting the second wasn t working as well

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its not a big issue just change your server name see where to server name change   how to find server name  open run write  cmd  write in console window  quot Hostname quot    your server name will show you thank you

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In my instance  the name of the connectionString in the web config file was spelled wrong   This is the name of the database context Entity Framework uses   I guess this is the error you get when EF can t match up the connectionString name with the context

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Change your   SQLEXPRESS and add your SQL express name only and it works for me    lt add name  BlogDbContext  connectionString  data source your name here  initial catalog CodeFirstDemo  integrated security True  providerName  System Data SqlClient   gt

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We got the same issue recently  We found out that the code is looking for the connection string named  LocalSqlServer  in the machine confg file  We added this line and it is working fine

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In my case I searched for services  Then found a service called  SQL Server SQLEXPRESS   Then right click on that  Select properties  Then click start  That s all  Solved the issue

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The issue is caused by the DNS failing to resolve the hostname  Try using the IP address instead of the  computer name

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This problem took me about one day  on one of mine ASP NET MVC project fortunately i had the problem on my machine and not in production environment  so comparing web config i see  and removing that the error disappeared    a true challenge connect the SQL Server error 26 to this problem

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Same issue  In my case I solved setting the project as the  StartUp Project

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i had this issue  and fixed it  the problem seemed to be this   wrong    lt add key  aaa  value  server  abc SQL2K8  database bbb uid ccc password ddd     gt    right   lt add key  aaa  value  server abc SQL2K8 database bbb uid ccc password ddd     gt

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If you are connecting from Windows machine A to Windows machine B  server with SQL Server installed   and are getting this error  you need to do the following   On machine B   1   turn on the Windows service called  SQL Server Browser  and start the service  2   in the Windows firewall  enable incoming port UDP 1434  in case SQL Server Management Studio on machine A is connecting or a program on machine A is connecting   3   in the Windows firewall  enable incoming port TCP 1433  in case there is a telnet connection   4   in SQL Server Configuration Manager  enable TCP IP protocol for port 1433

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For me the issue was that the DNS record was wrong      The following  which proved very helpful  is largely taken from this blog post   This error message is actually pretty specific and the solution quite simple   You get this error message only if you are trying to connect to a SQL Server named instance  For a default instance  you never see this because even if we failed at this stage  i e  error locating server instance specified   we will continue to try connect using default values  e g default TCP port 1433  default pipe name for Named Pipes   Every time a client makes a connection to SQL Server named instance  we will send a SSRP UDP packet to the server machine UDP port 1434  We need this step to know configuration information of the SQL instance  e g   protocols enabled  TCP port  pipe name etc  Without this information the client does not know how to connect and it fails with this error message   In a word  the reason that we get this error message is the client stack could not receive SSRP response UDP packet from SQL Browser  In order to isolate the exact issue follow these steps    Make sure your server name is correct  e g   no typo on the name  Make sure your instance name is correct and there is actually such an instance on your target machine   Be aware that some applications convert   to    Make sure the server machine is reachable  e g  DNS can be resolve correctly  you are able to ping the server  not always true   Make sure the SQL Browser service is running on the server  If the firewall is enabled on the server  you need to put sqlbrowser exe and or UDP port 1434 into exception    There is one corner case where you may still fail after you checked steps 1 to 4  It also may happen when    your server is a named instance on cluster or on a multi-homed machine your client is a Vista machine with Firewall on     A tool which could prove useful  it did for me  is PortQry  If this command returns information and it contains your target instance  then you can rule out possiblity 4  and 5  above  meaning you do have a SQL Browser running and your firewall does not block SQL Browser UDP packet  In this case  you can check other possible issues such as an incorrect connection string   As a final note  the error message for the same issue when you use SNAC is   SQL Native Client SQL Network Interfaces  Error Locating Server Instance Specified  xFFFFFFFF    Microsoft recently released a guided walk through that can serve as a one stop shop to troubleshoot a majority of connectivity issues to SQL Server  Solving Connectivity errors to SQL Server

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I had been experiencing the same problem  in my ASP NET MVC 4 application    The way I solved it  was in the DatabaseContext  By passing down the name of the connection string I wanted to use through the base constructor   public class DatabaseContext   DbContext        public DatabaseContext             base  DefaultConnection       lt -- this is what i added                   public DbSet lt SomeModel gt  SomeModels   get  set

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I had the same error and I started the SQL Server Express service and it worked  Hope this helps

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Goto window R and type services msc and press enter   Then start SQL server manually if not automatically started   Then you try to login  it must be works

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The answer is in the error message itself   Error Locating Server Instance Specified   Basically  you ve got the wrong server instance in the connection string  i e  this bit   Data Source MSSQL2008-1   is wrong and not pointing to the server  or the servername doesn t resolve to an IP address  Two other posibilities   1  the SQL Browser Service on the box running SQL Server isn t running or  2  Windows Firewall  or some other firewall  on the SQL box is denying incoming connections   Ultimately  if the servername is correct  then it turns into a networking problem  and you need to find out why the client cannot connect to the server  and this will be more likely to be a basic networking problem than a SQL Server configuration problem

[asp.net] SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified

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