问mscorlib.dll中出现'System.Data.SqlClient.SqlException‘类型的异常，但未在用户代码中处理

EN

An exception of type 'System.Data.SqlClient.SqlException' occurred in 
mscorlib.dll but was not handled in user code

Additional information: 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: 50 - Local Database Runtime error occurred. The 
specified LocalDB instance does not exist.)

Line 22:             var roleMgr = new RoleManager<IdentityRole>(roleStore);
Line 23: 
Line 24:             if (!roleMgr.RoleExists("canEdit"))
Line 25:                 IdRoleResult = roleMgr.Create(new IdentityRole { Name = "canEdit" });
Line 26: 

[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: 50 - Local Database Runtime error occurred. The specified LocalDB instance does not exist.
)]
   System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, DbConnectionPool pool, String accessToken, Boolean applyTransientFaultHandling) +821
   System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions) +332
   System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions) +38
   System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) +699
   System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection) +89
   System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection) +426
   System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection) +78
   System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection) +191
   System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +154
   System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) +21
   System.Data.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry) +90
   System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry) +217
   System.Data.SqlClient.SqlConnection.Open() +96
   System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.<Open>b__36(DbConnection t, DbConnectionInterceptionContext c) +36
   System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch(TTarget target, Action`2 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed) +138
   System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext) +477
   System.Data.Entity.SqlServer.<>c__DisplayClass33.<UsingConnection>b__32() +520
   System.Data.Entity.SqlServer.<>c__DisplayClass1.<Execute>b__0() +34
   System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Func`1 operation) +251
   System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation) +196
   System.Data.Entity.SqlServer.SqlProviderServices.UsingConnection(DbConnection sqlConnection, Action`1 act) +276
   System.Data.Entity.SqlServer.SqlProviderServices.UsingMasterConnection(DbConnection sqlConnection, Action`1 act) +545
   System.Data.Entity.SqlServer.SqlProviderServices.CreateDatabaseFromScript(Nullable`1 commandTimeout, DbConnection sqlConnection, String createDatabaseScript) +151
   System.Data.Entity.SqlServer.SqlProviderServices.DbCreateDatabase(DbConnection connection, Nullable`1 commandTimeout, StoreItemCollection storeItemCollection) +287
   System.Data.Entity.Core.Common.DbProviderServices.CreateDatabase(DbConnection connection, Nullable`1 commandTimeout, StoreItemCollection storeItemCollection) +111
   System.Data.Entity.Core.Objects.ObjectContext.CreateDatabase() +236
   System.Data.Entity.Migrations.Utilities.DatabaseCreator.Create(DbConnection connection) +143
   System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase) +207
   System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase) +42
   System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration) +136
   System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update() +33
   System.Data.Entity.Internal.DatabaseCreator.CreateDatabase(InternalContext internalContext, Func`3 createMigrator, ObjectContext objectContext) +175
   System.Data.Entity.Internal.InternalContext.CreateDatabase(ObjectContext objectContext, DatabaseExistenceState existenceState) +150
   System.Data.Entity.Database.Create(DatabaseExistenceState existenceState) +444
   System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context) +290
   System.Data.Entity.Internal.<>c__DisplayClassf`1.<CreateInitializationAction>b__e() +165
   System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action) +110
   System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() +660
   System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c) +31
   System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input) +143
   System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action) +292
   System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase() +123
   System.Data.Entity.Internal.InternalContext.Initialize() +42
   System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +39
   System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() +137
   System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext() +38
   System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider() +99
   System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(IQueryable`1 source, Expression`1 predicate, CancellationToken cancellationToken) +197
   System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(IQueryable`1 source, Expression`1 predicate) +233
   Microsoft.AspNet.Identity.EntityFramework.RoleStore`3.FindByNameAsync(String roleName) +1120
   Microsoft.AspNet.Identity.<FindByNameAsync>d__13.MoveNext() +278
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
   System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +28
   Microsoft.AspNet.Identity.CultureAwaiter`1.GetResult() +123
   Microsoft.AspNet.Identity.<RoleExistsAsync>d__d.MoveNext() +612
   System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
   System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
   System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +28
   Microsoft.AspNet.Identity.AsyncHelper.RunSync(Func`1 func) +244
   Microsoft.AspNet.Identity.RoleManagerExtensions.RoleExists(RoleManager`2 manager, String roleName) +241
   Starlane.Logic.RoleActions.AddUserAndRole() in F:\WEBENGINEERING\Starlane\Starlane\Logic\RoleActions.cs:24
   Starlane.Global.Application_Start(Object sender, EventArgs e) in F:\WEBENGINEERING\Starlane\Starlane\Global.asax.cs:28

[HttpException (0x80004005): 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: 50 - Local Database Runtime error occurred. The specified LocalDB instance does not exist.
)]
   System.Web.HttpApplicationFactory.EnsureAppStartCalledForIntegratedMode(HttpContext context, HttpApplication app) +10063289
   System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +118
   System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +173
   System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +336
   System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +296

[HttpException (0x80004005): 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: 50 - Local Database Runtime error occurred. The specified LocalDB instance does not exist.
)]
   System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +10044576
   System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +95
   System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +254

<connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=(LocalDb)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\aspnet-Starlane-20170802095040.mdf;Initial Catalog=aspnet-Starlane-20170802095040;Integrated Security=True" providerName="System.Data.SqlClient"/>
    <add name="Starlane" connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename=|DataDirectory|\starlane.mdf;Integrated Security=True" providerName="System.Data.SqlClient"/>
  </connectionStrings>