No database provider has been configured 🟪 .NET

InvalidOperationException: No database provider has been configured for this DbContext

EF Core created a DbContext without UseSqlServer/UseNpgsql/UseSqlite — typically because the context was newed up manually or registered without options.

Seen on: .NET

Meaning

Configure the provider in AddDbContext or OnConfiguring, and make sure the DbContext has a constructor accepting DbContextOptions<T> passed to base.

Common causes

  • DbContext created with new instead of DI
  • Missing constructor taking DbContextOptions<T>
  • AddDbContext without a provider
  • Design-time tools can’t find the configuration

⚡ Quick fix

  1. Register: services.AddDbContext<AppDb>(o => o.UseSqlServer(cs))
  2. Add public AppDb(DbContextOptions<AppDb> options) : base(options) {}
  3. Resolve the context from DI

Detailed fix by platform

C#

  1. csharp
    public class AppDb : DbContext
{
    public AppDb(DbContextOptions<AppDb> options) : base(options) { }
}

How to diagnose

  1. Registration — AddDbContext call
  2. Constructor — Accepts options?
  3. Creation — new vs DI

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