Using Oracle database for the default ASP.NET MVC application

You have to use ODP.NET API instead of SqlClient provider. The System.Data.SqlClient classes are for Microsoft SQL server database only.

EDIT:

Oracle article : Oracle Providers for ASP.NET Installation

I've used DevArt Oracle Connector I modified my web.config like this

<?xml version="1.0" encoding="utf-8"?><!--  For more information on how to configure your ASP.NET application, please visit  http://go.microsoft.com/fwlink/?LinkId=301880  --><configuration>  <configSections>    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->  </configSections>  <connectionStrings >    <!--<add name="DefaultConnection" connectionString="Data Source=(LocalDb)\v11.0;AttachDbFilename=|DataDirectory|\aspnet-oapp-20140623054602.mdf;Initial Catalog=aspnet-oapp-20140623054602;Integrated Security=True"      providerName="System.Data.SqlClient" />-->    <add name="DefaultConnection"  connectionString="User Id=demouser;Password=demo123;Server=oracle;Direct=True;Sid=orcl;" providerName="Devart.Data.Oracle" />  </connectionStrings>  <appSettings>    <add key="webpages:Version" value="3.0.0.0" />    <add key="webpages:Enabled" value="false" />    <add key="ClientValidationEnabled" value="true" />    <add key="UnobtrusiveJavaScriptEnabled" value="true" />  </appSettings>  <system.web>    <authentication mode="None" />    <compilation debug="true" targetFramework="4.5" />    <httpRuntime targetFramework="4.5" />    <roleManager enabled="true" defaultProvider="OracleExtendedRoleProvider">      <providers>        <clear />        <remove name="OracleExtendedRoleProvider" />        <!--<add name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/" />-->        <add name="OracleExtendedRoleProvider" type="Devart.Data.Oracle.Web.Providers.OracleExtendedRoleProvider, Devart.Data.Oracle.Web,              Version=8.4.181.4, Culture=neutral, PublicKeyToken=09af7300eec23701" connectionStringName="DefaultConnection" />      </providers>    </roleManager>    <profile defaultProvider="OracleExtendedProfileProvider">      <!-- <properties>        <add name="friendlyName"/>      </properties>-->      <providers>        <remove name="OracleExtendedProfileProvider" />        <add name="OracleExtendedProfileProvider" type="Devart.Data.Oracle.Web.Providers.OracleProfileProvider, Devart.Data.Oracle.Web,               Version=8.4.181.4, Culture=neutral, PublicKeyToken=09af7300eec23701" connectionStringName="DefaultConnection" />      </providers>    </profile>    <membership defaultProvider="OracleExtendedMembershipProvider">      <providers>        <remove name="OracleExtendedMembershipProvider" />        <add name="OracleExtendedMembershipProvider" type="Devart.Data.Oracle.Web.Providers.OracleMembershipProvider, Devart.Data.Oracle.Web,               Version=8.4.181.4 Culture=neutral, PublicKeyToken=09af7300eec23701" connectionStringName="DefaultConnection" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="true" requiresUniqueEmail="false" passwordFormat="Hashed" maxInvalidPasswordAttempts="5" passwordAttemptWindow="10" />      </providers>    </membership>    <sessionState mode="InProc" customProvider="OracleSessionProvider">      <providers>        <add name="OracleSessionProvider" type="Devart.Data.Oracle.Web.Providers.OracleSessionStateStore,Devart.Data.Oracle.Web,               Version=8.4.181.4, Culture=neutral, PublicKeyToken=09af7300eec23701" connectionStringName="OracleServices" />      </providers>    </sessionState>    <siteMap defaultProvider="OracleSiteMapProvider">      <providers>        <add name="OracleSiteMapProvider" type="Devart.Data.Oracle.Web.Providers.OracleSiteMapProvider, Devart.Data.Oracle.Web,               Version=8.4.181.4, Culture=neutral, PublicKeyToken=09AF7300EEC23701" connectionStringName="DefaultConnection" securityTrimmingEnabled="true" />      </providers>    </siteMap>  </system.web>  <system.webServer>    <modules>      <remove name="FormsAuthenticationModule" />    </modules>  </system.webServer>  <runtime>    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">      <dependentAssembly>        <assemblyIdentity name="System.Web.WebPages.Razor" publicKeyToken="31BF3856AD364E35" culture="neutral" />        <bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />      </dependentAssembly>      <dependentAssembly>        <assemblyIdentity name="System.Web.Razor" publicKeyToken="31BF3856AD364E35" culture="neutral" />        <bindingRedirect oldVersion="0.0.0.0-3.0.0.0" newVersion="3.0.0.0" />      </dependentAssembly>      <dependentAssembly>        <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />        <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />      </dependentAssembly>      <dependentAssembly>        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />        <bindingRedirect oldVersion="1.0.0.0-5.1.0.0" newVersion="5.1.0.0" />      </dependentAssembly>      <dependentAssembly>        <assemblyIdentity name="System.Web.Optimization" publicKeyToken="31bf3856ad364e35" />        <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0" />      </dependentAssembly>      <dependentAssembly>        <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />        <bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />      </dependentAssembly>      <dependentAssembly>        <assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" />        <bindingRedirect oldVersion="0.0.0.0-1.5.2.14234" newVersion="1.5.2.14234" />      </dependentAssembly>    </assemblyBinding>  </runtime>  <entityFramework codeConfigurationType="oapp.Models.MyDbConfiguration, oapp">    <!-- <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">      <parameters>        <parameter value="v11.0"/>      </parameters>    </defaultConnectionFactory>-->    <providers>      <provider invariantName="Devart.Data.Oracle" type="Devart.Data.Oracle.Entity.OracleEntityProviderServices, Devart.Data.Oracle.Entity, Version=8.4.181.6, Culture=neutral, PublicKeyToken=09af7300eec23701" />      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />    </providers>    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">      <parameters>        <parameter value="v11.0" />      </parameters>    </defaultConnectionFactory>  </entityFramework></configuration>

This worked for me.After this too I got issue in ProviderService Project was unable to find it. so I modified this code in IdentityModels.cs

using System.Security.Claims;using System.Threading.Tasks;using Microsoft.AspNet.Identity;using Microsoft.AspNet.Identity.EntityFramework;using System.Data.Entity;using System.Data.Entity.Migrations;namespace oapp.Models{    // You can add profile data for the user by adding more properties to your ApplicationUser class, please visit http://go.microsoft.com/fwlink/?LinkID=317594 to learn more.    public class ApplicationUser : IdentityUser    {        public async Task<ClaimsIdentity> GenerateUserIdentityAsync(UserManager<ApplicationUser> manager)        {            // Note the authenticationType must match the one defined in CookieAuthenticationOptions.AuthenticationType            var userIdentity = await manager.CreateIdentityAsync(this, DefaultAuthenticationTypes.ApplicationCookie);            // Add custom user claims here            return userIdentity;        }    }    public class ApplicationDbContext : IdentityDbContext<ApplicationUser>    {        public ApplicationDbContext()            : base("DefaultConnection", throwIfV1Schema: false)        {        }        public static ApplicationDbContext Create()        {            return new ApplicationDbContext();        }        static ApplicationDbContext()        {            var config = Devart.Data.Oracle.Entity.Configuration.OracleEntityProviderConfig.Instance;            config.CodeFirstOptions.TruncateLongDefaultNames = true;            Database.SetInitializer(new MigrateDatabaseToLatestVersion<ApplicationDbContext, Configuration>());        }        protected override void OnModelCreating(DbModelBuilder modelBuilder)        {            base.OnModelCreating(modelBuilder);            modelBuilder              .Properties()              .Where(p => p.PropertyType == typeof(string) &&                          !p.Name.Contains("Id") &&                          !p.Name.Contains("Provider"))              .Configure(p => p.HasMaxLength(256));        }    }    internal class Configuration : DbMigrationsConfiguration<ApplicationDbContext>    {        public Configuration()        {            AutomaticMigrationsEnabled = true;            SetSqlGenerator("Devart.Data.Oracle", new Devart.Data.Oracle.Entity.Migrations.OracleEntityMigrationSqlGenerator());        }    }    public class MyDbConfiguration :  DbConfiguration    {        public MyDbConfiguration()        {           // this.AddDbProviderServices("Devart.Data.Oracle", new Devart.Data.Oracle.Entity.OracleEntityProviderServices());            this.SetProviderServices("Devart.Data.Oracle", new Devart.Data.Oracle.Entity.OracleEntityProviderServices());        }    }}

hope it will work for you too.

You have to use "ODP.NET" API instead of "SqlClient" provider. you can find more details from THIS blog post. After setup according to the process, you will no need to change any connection strings.