Migrating ASP.NET 4.8 to .NET Core 10: Complete Guide

Step 4: Rewrite the HTTP Pipeline

public class MvcApplication : HttpApplication
{
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
}
protected void Application_BeginRequest(object sender, EventArgs e)
{
// Custom request logic
}
}

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllersWithViews();
builder.Services.AddDbContext<AppDbContext>(opt =>
opt.UseSqlServer(builder.Configuration.GetConnectionString("Default")));
var app = builder.Build();
app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.Use(async (ctx, next) =>
{
// Custom request logic (replaces Application_BeginRequest)
await next();
});
app.MapControllerRoute("default", "{controller=Home}/{action=Index}/{id?}");
app.Run();

Step 5: Convert Configuration

<connectionStrings>
<add name="Default" connectionString="Server=db;Database=YourApp;..." />
</connectionStrings>
<appSettings>
<add key="StripeApiKey" value="sk_test_..." />
</appSettings>

{
"ConnectionStrings": {
"Default": "Server=db;Database=YourApp;..."
},
"Stripe": {
"ApiKey": "sk_test_..."
}
}

Step 6: Migrate Entity Framework 6 → EF Core 10

EF6 and EF Core have similar APIs but different runtime characteristics. The 80% case is straightforward:

// EF6 (Framework)
public class AppContext : DbContext
{
public AppContext() : base("name=Default") { }
public DbSet<Order> Orders { get; set; }
}
// EF Core 10
public class AppContext : DbContext
{
public AppContext(DbContextOptions<AppContext> options) : base(options) { }
public DbSet<Order> Orders { get; set; }
}
// In Program.cs:
builder.Services.AddDbContext<AppContext>(opt =>
opt.UseSqlServer(builder.Configuration.GetConnectionString("Default")));

Step 7: Replace WebForms (If You Have Them)

There's no .NET Core port for WebForms. The migration paths in order of preference:

| Page Type | Recommended Target |

|---|---|

| Form-heavy CRUD | Razor Pages (closest mental model) |

| Data-driven views | ASP.NET Core MVC |

| Rich interactive UIs | Blazor Server (preserves server-side state) |

| Public marketing | Static SSR (Blazor) or MVC |

Step 8: Test Strategy

Three layers of testing during migration:

• Compatibility tests — port your existing unit tests; they'll mostly work as-is
• Behavioral parity — automated UI tests (Playwright, Selenium) hitting both old and new versions with the same inputs, comparing outputs
• Load tests — k6 or NBomber against the new version; you should see significantly better throughput and lower p95 latency

We typically see 3–10× throughput improvements on migrated apps just from the runtime change — before any architectural improvements.

Step 9: Deploy to Production

<configuration>
<location path="." inheritInChildApplications="false">
<system.webServer>
<handlers>
<add name="aspNetCore" path="" verb="" modules="AspNetCoreModuleV2" resourceType="Unspecified" />
</handlers>
<aspNetCore processPath=".\YourApp.exe" stdoutLogEnabled="false" hostingModel="inprocess" />
</system.webServer>
</location>
</configuration>

Side-by-Side Hosting on Adaptive

The biggest practical advantage of Adaptive's hosting plans for migrations: every plan supports both .NET Framework and .NET 10 LTS simultaneously, with dedicated IIS Application Pools per site.

| Plan | Websites | RAM per Pool | Price |

|---|---|---|---|

| Developer | 2 | 1 GB | $9.49/mo |

| Business | 5 | 2 GB | $17.49/mo |

| Professional | 10 | 4 GB | $27.49/mo |

You can host the legacy 4.8 app and the new .NET 10 version on the same plan, route traffic between them via DNS or reverse proxy, and migrate piece-by-piece without buying separate infrastructure.

Frequently Asked Questions

How long does an ASP.NET 4.8 → .NET 10 migration typically take?

For a typical MVC 5 + EF6 application (30K LOC, no WebForms), 4–8 weeks of focused engineering work. WebForms-heavy applications take significantly longer because the views must be rewritten. Side-by-side migrations stretch longer in calendar time but keep continuous releases.

Can I run .NET Framework 4.8 and .NET 10 on the same server?

Yes. IIS happily hosts multiple application pools, each pinned to a different .NET runtime. On Adaptive's hosting plans, every plan ships with both runtimes installed; you select per-app.

What's the hardest part of the migration?

For most apps: the HTTP pipeline rewrite (HttpModule → middleware) and any custom configuration providers. For WebForms apps: rewriting the views — this is genuinely a rewrite, not a port.

Does EF6 code work without changes in EF Core?

Should I migrate to .NET 8 LTS or .NET 10 LTS?

.NET 10 LTS for new projects in 2026 — it's supported until November 2028 and has the latest performance work. .NET 8 LTS is fine if you're shipping in the next few months and need a stable target (.NET 8 has mainstream support until November 2026). See our .NET Core 10 hosting guide for the full feature set.

Will my SQL Server database need to change?

No schema changes are required. EF Core 10 connects to SQL Server 2008+ without modification. However, you'll unlock more performance if you upgrade to SQL Server 2022 (which every Adaptive plan includes): Query Store, ledger tables, native JSON, Always Encrypted with enclaves.

What about WCF services?

title: Host Both Legacy ASP.NET 4.8 and Modern .NET 10 on the Same Plan
description: Dedicated IIS Application Pools per site. ASP.NET 2.0 through 4.8 plus .NET 7/8/9/10 LTS. SQL Server 2022 + MariaDB. 99.99% uptime SLA. Plans from $9.49/mo.
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