我目前收到错误：
System.Data.SqlClient.SqlException：用户'null'登录失败。
当试图从Asp.net web api获取令牌时。这仅发生在Azure而不是任何其他服务器上。即使在本地连接到Azure上的数据库运行站点也没有问题。它似乎是出于某种原因试图创建数据库而没有它的权限。
此错误的堆栈跟踪是：
[SqlException (0x80131904): Login failed for user 'null'.]
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) +497
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) +10
System.Data.Entity.Infrastructure.Interception.InternalDispatcher`1.Dispatch(TTarget target, Action`2 operation, TInterceptionContext interceptionContext, Action`3 executing, Action`3 executed) +72
System.Data.Entity.Infrastructure.Interception.DbConnectionDispatcher.Open(DbConnection connection, DbInterceptionContext interceptionContext) +359
System.Data.Entity.SqlServer.<>c__DisplayClass33.<UsingConnection>b__32() +426
System.Data.Entity.SqlServer.<>c__DisplayClass1.<Execute>b__0() +10
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Func`1 operation) +189
System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute(Action operation) +77
System.Data.Entity.SqlServer.SqlProviderServices.UsingConnection(DbConnection sqlConnection, Action`1 act) +174
System.Data.Entity.SqlServer.SqlProviderServices.UsingMasterConnection(DbConnection sqlConnection, Action`1 act) +556
System.Data.Entity.SqlServer.SqlProviderServices.CreateDatabaseFromScript(Nullable`1 commandTimeout, DbConnection sqlConnection, String createDatabaseScript) +86
System.Data.Entity.SqlServer.SqlProviderServices.DbCreateDatabase(DbConnection connection, Nullable`1 commandTimeout, StoreItemCollection storeItemCollection) +164
System.Data.Entity.Core.Common.DbProviderServices.CreateDatabase(DbConnection connection, Nullable`1 commandTimeout, StoreItemCollection storeItemCollection) +76
System.Data.Entity.Core.Objects.ObjectContext.CreateDatabase() +134
System.Data.Entity.Migrations.Utilities.DatabaseCreator.Create(DbConnection connection) +119
System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase) +142
System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration) +78
System.Data.Entity.Internal.DatabaseCreator.CreateDatabase(InternalContext internalContext, Func`3 createMigrator, ObjectContext objectContext) +89
System.Data.Entity.Internal.InternalContext.CreateDatabase(ObjectContext objectContext, DatabaseExistenceState existenceState) +116
System.Data.Entity.Database.Create(DatabaseExistenceState existenceState) +218
System.Data.Entity.CreateDatabaseIfNotExists`1.InitializeDatabase(TContext context) +149
System.Data.Entity.Internal.<>c__DisplayClassf`1.<CreateInitializationAction>b__e() +76
System.Data.Entity.Internal.InternalContext.PerformInitializationAction(Action action) +60
System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() +357
System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c) +7
System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input) +110
System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action) +198
System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase() +73
System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +28
System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() +53
System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext() +15
System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider() +38
System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(IQueryable`1 source, Expression`1 predicate, CancellationToken cancellationToken) +138
System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync(IQueryable`1 source, Expression`1 predicate) +145
Microsoft.AspNet.Identity.EntityFramework.<GetUserAggregateAsync>d__6c.MoveNext() +483
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.AspNet.Identity.CultureAwaiter`1.GetResult() +59
Microsoft.AspNet.Identity.<FindAsync>d__12.MoveNext() +267
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
com.phiresky.tatami.api.Providers.<GrantResourceOwnerCredentials>d__2.MoveNext() +234
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Security.OAuth.<InvokeTokenEndpointResourceOwnerPasswordCredentialsGrantAsync>d__3f.MoveNext() +466
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task) +25
Microsoft.Owin.Security.OAuth.<InvokeTokenEndpointAsync>d__22.MoveNext() +1552
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task) +25
Microsoft.Owin.Security.OAuth.<InvokeAsync>d__0.MoveNext() +1103
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Security.Infrastructure.<Invoke>d__0.MoveNext() +435
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Security.Infrastructure.<Invoke>d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Security.Infrastructure.<Invoke>d__0.MoveNext() +638
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.AspNet.Identity.Owin.<Invoke>d__0.MoveNext() +404
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.AspNet.Identity.Owin.<Invoke>d__0.MoveNext() +404
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.<RunApp>d__5.MoveNext() +182
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +92
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.<DoFinalWork>d__2.MoveNext() +180
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.StageAsyncResult.End(IAsyncResult ar) +69
Microsoft.Owin.Host.SystemWeb.IntegratedPipeline.IntegratedPipelineContext.EndFinalWork(IAsyncResult ar) +64
System.Web.AsyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +380
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155
得到它了！很奇怪，但我不得不进入Azure门户 - > App Services-> {My App} - > Application Settings
Connection Strings有一个设置。连接字符串的值为User null。我把它改成我的常规连接字符串，现在它工作正常。
在我的情况下使用VS 2017和IIS8的实体框架。
我通过执行ff解决了这个错误：