What causes "The migration '{migrationName}' was not found." in dotnet/efcore?

List available migrations (`dotnet ef migrations list`) and use an exact name/id.

dotnet/efcore · error · InvalidOperationException

The migration '{migrationName}' was not found.

Error message

The migration '{migrationName}' was not found.

What it means

Thrown by MigrationsAssemblyExtensions.GetMigrationId when `IMigrationsAssembly.FindMigrationId` returns null for the requested name or id. EF could not locate a registered migration matching the supplied string, so a lookup that requires the migration to exist fails.

Source

Thrown at src/EFCore.Relational/Migrations/MigrationsAssemblyExtensions.cs:35

    /// </summary>
    /// <remarks>
    ///     <para>
    ///         An exception is thrown if the migration was not found--use
    ///         <see cref="IMigrationsAssembly.FindMigrationId" /> if the migration may not exist.
    ///     </para>
    ///     <para>
    ///         See <see href="https://aka.ms/efcore-docs-migrations">Database migrations</see> for more information and examples.
    ///     </para>
    /// </remarks>
    /// <param name="assembly">The assembly.</param>
    /// <param name="nameOrId">The name or identifier to lookup.</param>
    /// <returns>The identifier of the migration.</returns>
    public static string GetMigrationId(this IMigrationsAssembly assembly, string nameOrId)
    {
        Check.NotEmpty(nameOrId);

        var id = assembly.FindMigrationId(nameOrId);
        return id ?? throw new InvalidOperationException(RelationalStrings.MigrationNotFound(nameOrId));
    }
}

View on GitHub (pinned to dbf9771522)

Solutions

List available migrations (`dotnet ef migrations list`) and use an exact name/id.
Ensure the migrations assembly is configured: `.MigrationsAssembly("MyProject.Migrations")`.
Add the missing migration via `dotnet ef migrations add <Name>` if it does not exist yet.
Check for typos and trailing/leading spaces in the supplied name.

Example fix

// before
db.Database.Migrate("AddFos"); // typo
// after
db.Database.Migrate("AddFoos");

Defensive patterns

Strategy: type-guard

Validate before calling

// Use the non-throwing lookup before calling Migrate with a target name.
var id = db.GetService<IMigrationsAssembly>().FindMigrationId(name);
if (id is null)
    throw new InvalidOperationException($"Migration '{name}' not found. Available: "
        + string.Join(", ", db.GetService<IMigrationsAssembly>().Migrations.Keys));
db.Database.Migrate(id);

Type guard

bool MigrationExists(IMigrationsAssembly asm, string nameOrId)
    => asm.FindMigrationId(nameOrId) is not null;

Prevention

Use `FindMigrationId` (returns null) instead of `GetMigrationId` (throws) when the migration may not exist.
List migrations with `dotnet ef migrations list` before scripting updates.
Configure the correct `.MigrationsAssembly(...)` so names resolve.

When it happens

Trigger: Calling `Database.Migrate("SomeName")` or `dotnet ef database update SomeName` with a migration name/id that does not exist in the configured migrations assembly; typos; migration not yet added; wrong assembly configured.

Common situations: Typo in the migration name; calling `Migrate` with a name from a different DbContext/assembly; migrations registered in a separate assembly not passed to `MigrationsAssembly`; deleted/renamed migrations.

Related errors

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/0492abe68a8d4e5a. Report an issue: GitHub.