与 SQL 服务器建立连接时出现网络相关错误
A Network related error occurred while establishing a connection to SQL Server
我有时会或有时不会遇到这个错误（有时应用 运行 正确），但现在它一次又一次地给我错误。
我 运行 在本地 host.Following 我的应用程序是错误的详细信息。
我不确定为什么我会遇到这个错误，我想我做错了什么。由于这个错误，我无法进一步处理我的项目。
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)
Web.config:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
<sectionGroup name="dotNetOpenAuth" type="DotNetOpenAuth.Configuration.DotNetOpenAuthSection, DotNetOpenAuth.Core">
<section name="messaging" type="DotNetOpenAuth.Configuration.MessagingElement, DotNetOpenAuth.Core" requirePermission="false" allowLocation="true" />
<section name="reporting" type="DotNetOpenAuth.Configuration.ReportingElement, DotNetOpenAuth.Core" requirePermission="false" allowLocation="true" />
<section name="openid" type="DotNetOpenAuth.Configuration.OpenIdElement, DotNetOpenAuth.OpenId" requirePermission="false" allowLocation="true" /><section name="oauth" type="DotNetOpenAuth.Configuration.OAuthElement, DotNetOpenAuth.OAuth" requirePermission="false" allowLocation="true" /></sectionGroup></configSections>
<connectionStrings>
<add name="DefaultConnection" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=mydb;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\mydb.mdf" providerName="System.Data.SqlClient" />
</connectionStrings>
<appSettings>
<add key="webpages:Version" value="3.0.0.0" /> <!--i have made new version from 2.0.0.0 to 3-->
<add key="webpages:Enabled" value="false" />
<add key="PreserveLoginUrl" value="true" />
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
</appSettings>
<system.web>
<compilation debug="true" targetFramework="4.5" />
<httpRuntime targetFramework="4.5" />
<authentication mode="Forms">
<forms loginUrl="~/Account/Login" timeout="2880" />
</authentication>
<pages>
<namespaces>
<add namespace="System.Web.Helpers" />
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Optimization" />
<add namespace="System.Web.Routing" />
<add namespace="System.Web.WebPages" />
</namespaces>
</pages>
</system.web>
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
<handlers>
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
<remove name="ExtensionlessUrlHandler-Integrated-4.0" />
<add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
<add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
</handlers>
</system.webServer>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="DotNetOpenAuth.Core" publicKeyToken="2780ccd10d57b246" />
<bindingRedirect oldVersion="0.0.0.0-4.3.0.0" newVersion="4.3.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="DotNetOpenAuth.AspNet" publicKeyToken="2780ccd10d57b246" />
<bindingRedirect oldVersion="0.0.0.0-4.3.0.0" newVersion="4.3.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="3.0.0.0" /><!--i have made new version from 2.0.0.0 to 3-->
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-5.2.2.0" newVersion="5.2.2.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-1.6.5135.21930" newVersion="1.6.5135.21930" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System" publicKeyToken="b77a5c561934e089" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Antlr3.Runtime" publicKeyToken="eb42632606e9261f" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-3.5.0.2" newVersion="3.5.0.2" />
</dependentAssembly>
</assemblyBinding>
<!--This prevents the Windows Event Log from frequently logging that HMAC1 is being used (when the other party needs it). <legacyHMACWarning enabled="0" /> When targeting ASP.NET MVC 3, this assemblyBinding makes MVC 1 and 2 references relink
to MVC 3 so libraries such as DotNetOpenAuth that compile against MVC 1 will work with it.-->
</runtime>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="v11.0" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>
</entityFramework>
<system.net>
<defaultProxy enabled="true" />
<settings>
<!--This setting causes .NET to check certificate revocation lists (CRL)
before trusting HTTPS certificates. But this setting tends to not
be allowed in shared hosting environments.-->
<servicePointManager checkCertificateRevocationList="true" />
</settings>
</system.net><dotNetOpenAuth>
<messaging>
<untrustedWebRequest>
<whitelistHosts>
<!--Uncomment to enable communication with localhost (should generally not activate in production!)-->
<add name="localhost" />
</whitelistHosts>
</untrustedWebRequest>
</messaging>
<!--Allow DotNetOpenAuth to publish usage statistics to library authors to improve the library.-->
<!--<reporting enabled="true" />-->
<!--This is an optional configuration section where aspects of dotnetopenauth can be customized. For a complete set of configuration options see http://www.dotnetopenauth.net/developers/code-snippets/configuration-options/--> <openid>
<relyingParty>
<security requireSsl="false">
Uncomment the trustedProviders tag if your relying party should only accept positive assertions from a closed set of OpenID Providers.
<trustedProviders rejectAssertionsFromUntrustedProviders="true">
<add endpoint="https://www.google.com/accounts/o8/ud" />
</trustedProviders>
</security>
<behaviors>
<!--The following OPTIONAL behavior allows RPs to use SREG only, but be compatible
with OPs that use Attribute Exchange (in various formats).-->
<add type="DotNetOpenAuth.OpenId.RelyingParty.Behaviors.AXFetchAsSregTransform, DotNetOpenAuth.OpenId.RelyingParty" />
</behaviors>
</relyingParty></openid></dotNetOpenAuth><uri>
<!--The uri section is necessary to turn on .NET 3.5 support for IDN (international domain names),
which is necessary for OpenID urls with unicode characters in the domain/host name.
It is also required to put the Uri class into RFC 3986 escaping mode, which OpenID and OAuth require.-->
<idn enabled="All" />
<iriParsing enabled="true" />
</uri></configuration>
Pls.Try 从以下位置清除日志文件并重新启动您的 sql 服务器：-
C:\Documents 和 Settings\Your pc-user\Local Settings\Application Data\Microsoft\Microsoft SQL 服务器 Data\SQLEXPRESS
我有时会或有时不会遇到这个错误（有时应用 运行 正确），但现在它一次又一次地给我错误。 我 运行 在本地 host.Following 我的应用程序是错误的详细信息。 我不确定为什么我会遇到这个错误，我想我做错了什么。由于这个错误，我无法进一步处理我的项目。
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)
Web.config:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
<sectionGroup name="dotNetOpenAuth" type="DotNetOpenAuth.Configuration.DotNetOpenAuthSection, DotNetOpenAuth.Core">
<section name="messaging" type="DotNetOpenAuth.Configuration.MessagingElement, DotNetOpenAuth.Core" requirePermission="false" allowLocation="true" />
<section name="reporting" type="DotNetOpenAuth.Configuration.ReportingElement, DotNetOpenAuth.Core" requirePermission="false" allowLocation="true" />
<section name="openid" type="DotNetOpenAuth.Configuration.OpenIdElement, DotNetOpenAuth.OpenId" requirePermission="false" allowLocation="true" /><section name="oauth" type="DotNetOpenAuth.Configuration.OAuthElement, DotNetOpenAuth.OAuth" requirePermission="false" allowLocation="true" /></sectionGroup></configSections>
<connectionStrings>
<add name="DefaultConnection" connectionString="Data Source=(LocalDb)\v11.0;Initial Catalog=mydb;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\mydb.mdf" providerName="System.Data.SqlClient" />
</connectionStrings>
<appSettings>
<add key="webpages:Version" value="3.0.0.0" /> <!--i have made new version from 2.0.0.0 to 3-->
<add key="webpages:Enabled" value="false" />
<add key="PreserveLoginUrl" value="true" />
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
</appSettings>
<system.web>
<compilation debug="true" targetFramework="4.5" />
<httpRuntime targetFramework="4.5" />
<authentication mode="Forms">
<forms loginUrl="~/Account/Login" timeout="2880" />
</authentication>
<pages>
<namespaces>
<add namespace="System.Web.Helpers" />
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Optimization" />
<add namespace="System.Web.Routing" />
<add namespace="System.Web.WebPages" />
</namespaces>
</pages>
</system.web>
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
<handlers>
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
<remove name="ExtensionlessUrlHandler-Integrated-4.0" />
<add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" />
<add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" />
<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
</handlers>
</system.webServer>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="DotNetOpenAuth.Core" publicKeyToken="2780ccd10d57b246" />
<bindingRedirect oldVersion="0.0.0.0-4.3.0.0" newVersion="4.3.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="DotNetOpenAuth.AspNet" publicKeyToken="2780ccd10d57b246" />
<bindingRedirect oldVersion="0.0.0.0-4.3.0.0" newVersion="4.3.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="3.0.0.0" /><!--i have made new version from 2.0.0.0 to 3-->
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-5.2.2.0" newVersion="5.2.2.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="0.0.0.0-1.6.5135.21930" newVersion="1.6.5135.21930" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System" publicKeyToken="b77a5c561934e089" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="30ad4fe6b2a6aeed" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-6.0.0.0" newVersion="6.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Net.Http" publicKeyToken="b03f5f7f11d50a3a" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="Antlr3.Runtime" publicKeyToken="eb42632606e9261f" culture="neutral" />
<bindingRedirect oldVersion="0.0.0.0-3.5.0.2" newVersion="3.5.0.2" />
</dependentAssembly>
</assemblyBinding>
<!--This prevents the Windows Event Log from frequently logging that HMAC1 is being used (when the other party needs it). <legacyHMACWarning enabled="0" /> When targeting ASP.NET MVC 3, this assemblyBinding makes MVC 1 and 2 references relink
to MVC 3 so libraries such as DotNetOpenAuth that compile against MVC 1 will work with it.-->
</runtime>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="v11.0" />
</parameters>
</defaultConnectionFactory>
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>
</entityFramework>
<system.net>
<defaultProxy enabled="true" />
<settings>
<!--This setting causes .NET to check certificate revocation lists (CRL)
before trusting HTTPS certificates. But this setting tends to not
be allowed in shared hosting environments.-->
<servicePointManager checkCertificateRevocationList="true" />
</settings>
</system.net><dotNetOpenAuth>
<messaging>
<untrustedWebRequest>
<whitelistHosts>
<!--Uncomment to enable communication with localhost (should generally not activate in production!)-->
<add name="localhost" />
</whitelistHosts>
</untrustedWebRequest>
</messaging>
<!--Allow DotNetOpenAuth to publish usage statistics to library authors to improve the library.-->
<!--<reporting enabled="true" />-->
<!--This is an optional configuration section where aspects of dotnetopenauth can be customized. For a complete set of configuration options see http://www.dotnetopenauth.net/developers/code-snippets/configuration-options/--> <openid>
<relyingParty>
<security requireSsl="false">
Uncomment the trustedProviders tag if your relying party should only accept positive assertions from a closed set of OpenID Providers.
<trustedProviders rejectAssertionsFromUntrustedProviders="true">
<add endpoint="https://www.google.com/accounts/o8/ud" />
</trustedProviders>
</security>
<behaviors>
<!--The following OPTIONAL behavior allows RPs to use SREG only, but be compatible
with OPs that use Attribute Exchange (in various formats).-->
<add type="DotNetOpenAuth.OpenId.RelyingParty.Behaviors.AXFetchAsSregTransform, DotNetOpenAuth.OpenId.RelyingParty" />
</behaviors>
</relyingParty></openid></dotNetOpenAuth><uri>
<!--The uri section is necessary to turn on .NET 3.5 support for IDN (international domain names),
which is necessary for OpenID urls with unicode characters in the domain/host name.
It is also required to put the Uri class into RFC 3986 escaping mode, which OpenID and OAuth require.-->
<idn enabled="All" />
<iriParsing enabled="true" />
</uri></configuration>
Pls.Try 从以下位置清除日志文件并重新启动您的 sql 服务器：-
C:\Documents 和 Settings\Your pc-user\Local Settings\Application Data\Microsoft\Microsoft SQL 服务器 Data\SQLEXPRESS