Problems Connecting to Remote Oracle Server Visual Studio 2015

Question

Alright so here's the Error I'm actually seeing:

An error occurred accessing the database. This usually means that the connection to the database failed. Check that the connection string is correct and that the appropriate DbContext constructor is being used to specify it or find it in the application's config file. See http://go.microsoft.com/fwlink/?LinkId=386386 for information on DbContext and connections. See the inner exception for details of the failure.

Oddly enough when I go to Visual Studio and open up Data Connections and Add in my remote server via that little tool, I can connect to it fine. However, I can't seem to connect to it via my app with the ConnectionStrings. Here's the full error log when connecting.

Using StartUp project 'Chime System'.
Using NuGet project 'Chime System'.
Specify the '-Verbose' flag to view the SQL statements being applied to the target database.
System.Data.Entity.Core.ProviderIncompatibleException: An error occurred 
accessing the database. This usually means that the connection to the database failed. Check that the connection string is correct and that the appropriate DbContext constructor is being used to specify it or find it in the application's config file. See http://go.microsoft.com/fwlink/?LinkId=386386 for information on DbContext and connections. See the inner exception for details of the failure. ---> System.Data.Entity.Core.ProviderIncompatibleException: The provider did not return a ProviderManifestToken string. ---> Oracle.ManagedDataAccess.Client.OracleException: ORA-12154: TNS:could not resolve the connect identifier specified ---> OracleInternal.Network.NetworkException: ORA-12154: TNS:could not resolve the connect identifier specified
at OracleInternal.Network.AddressResolution..ctor(String TNSAlias, String instanceName)
at OracleInternal.Network.OracleCommunication.DoConnect(String tnsDescriptor)
at OracleInternal.Network.OracleCommunication.Connect(String tnsDescriptor, Boolean doNAHandshake, String IName)
at OracleInternal.ServiceObjects.OracleConnectionImpl.Connect(ConnectionString cs, Boolean bOpenEndUserSession, CriteriaCtx criteriaCtx, String instanceName)
--- End of inner exception stack trace ---
at OracleInternal.ConnectionPool.PoolManager`3.Get(ConnectionString csWithDiffOrNewPwd, Boolean bGetForApp, CriteriaCtx criteriaCtx, String affinityInstanceName, Boolean bForceMatch)
at OracleInternal.ConnectionPool.OraclePoolManager.Get(ConnectionString csWithNewPassword, Boolean bGetForApp, CriteriaCtx criteriaCtx, String affinityInstanceName, Boolean bForceMatch)
at OracleInternal.ConnectionPool.OracleConnectionDispenser`3.Get(ConnectionString cs, PM conPM, ConnectionString pmCS, SecureString securedPassword, SecureString securedProxyPassword, CriteriaCtx criteriaCtx)
at Oracle.ManagedDataAccess.Client.OracleConnection.Open()
at Oracle.ManagedDataAccess.EntityFramework.EFOracleProviderServices.GetDbProviderManifestToken(DbConnection connection)
at System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
--- End of inner exception stack trace ---
at System.Data.Entity.Core.Common.DbProviderServices.GetProviderManifestToken(DbConnection connection)
at System.Data.Entity.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection)
--- End of inner exception stack trace ---
at System.Data.Entity.Utilities.DbProviderServicesExtensions.GetProviderManifestTokenChecked(DbProviderServices providerServices, DbConnection connection)
at System.Data.Entity.Infrastructure.DefaultManifestTokenResolver.<>c__DisplayClass1.<ResolveManifestToken>b__0(Tuple`3 k)
at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
at System.Data.Entity.Infrastructure.DefaultManifestTokenResolver.ResolveManifestToken(DbConnection connection)
at System.Data.Entity.Utilities.DbConnectionExtensions.GetProviderInfo(DbConnection connection, DbProviderManifest& providerManifest)
at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
at System.Data.Entity.Internal.LazyInternalContext.get_ModelBeingInitialized()
at System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(DbContext context, XmlWriter writer)
at System.Data.Entity.Utilities.DbContextExtensions.<>c__DisplayClass1.<GetModel>b__0(XmlWriter w)
at System.Data.Entity.Utilities.DbContextExtensions.GetModel(Action`1 writeXml)
at System.Data.Entity.Utilities.DbContextExtensions.GetModel(DbContext context)
at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration, DbContext usersContext, DatabaseExistenceState existenceState, Boolean calledByCreateDatabase)
at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration)
at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.GetMigrator()
at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.Run()
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
at System.Data.Entity.Migrations.Design.ToolingFacade.Update(String targetMigration, Boolean force)
at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
An error occurred accessing the database. This usually means that the connection to the database failed. Check that the connection string is correct and that the appropriate DbContext constructor is being used to specify it or find it in the application's config file. See http://go.microsoft.com/fwlink/?LinkId=386386 for information on DbContext and connections. See the inner exception for details of the failure.

Here's the connection strings info for the App:

<section name="oracle.manageddataaccess.client" type="OracleInternal.Common.ODPMSectionHandler, Oracle.ManagedDataAccess, Version=4.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342" /> 

<connectionStrings>
 <add name="defaultConnection" connectionString="Data Source=myServer;Persist Security Info=True;User ID=myUserID;Password=***********;" providerName="Oracle.ManagedDataAccess.Client"/>
</connectionStrings>

<oracle.manageddataaccess.client>
 <version number="*">
  <dataSources>
    <dataSource alias="SampleDataSource" descriptor="(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=myServer)(PORT=1521))(CONNECT_DATA=(SERVICE_NAME=ORCL)))" />
  </dataSources>
 </version>
</oracle.manageddataaccess.client>

and here's the ConnectionString from the data connection tool

connectionString = Data Source=myServer;Persist Security Info=True;User ID=myUserID;Password=***********;Unicode=True
provider = .NET Framework Data Provider for Oracle

So my question is what exactly am I doing wrong? Is my ConnectionStrings wrong in my app? I don't think it's my firewall either, though I'll double check this. Any help or advice you can offer would be helpful.

Answer 1

The important part of that error message is the following:

ORA-12154: TNS:could not resolve the connect identifier specified

You are trying to connect to a service named ORCL on the host myServer using port 1521.

First question: Can you ping that server? (i.e.: Does DNS work? Can you actually make a network connection to the server?) I'm guessing you can.

Second question: Is the Oracle listener running on that server?

You can find this out by having the oracle user on the database server run the following command: lsnrctl status The output of that command should show you the names of the services that are found on the server and the port number that the listener is running on. If it says no services then it's not running and it needs to be running. lsnrctl start as the oracle user will get it running and lsnrctl status will tell you what port and services are available.

If I had to guess I would say that your listener is running on the database server and it is listening on port 1521, but you are trying to access a service name that isn't being listened for (i.e.: You do not have an ORCL service on that server).