dotnet/efcore · error · OperationException

A migration name must be specified.

Error message

A migration name must be specified.

What it means

AddMigration / AddAndApplyMigration -> PrepareForMigration requires a non-empty migration name (line 438). The name becomes a file name and a class name, so an empty or whitespace string is rejected up front.

Source

Thrown at src/EFCore.Design/Design/Internal/MigrationsOperations.cs:440

        var migrationsAssembly = scope.ServiceProvider.GetRequiredService<IMigrationsAssembly>();
        var compiledAssembly = compiler.CompileMigration(migration, context.GetType());
        migrationsAssembly.AddMigrations(compiledAssembly);

        migrator.Migrate(migration.MigrationId);

        _reporter.WriteInformation(DesignStrings.MigrationCreatedAndApplied(migration.MigrationId));

        return files;
    }

    /// <summary>
    ///     Prepares common resources for migration operations.
    /// </summary>
    public virtual IServiceProvider PrepareForMigration(string name, DbContext context)
    {
        if (string.IsNullOrWhiteSpace(name))
        {
            throw new OperationException(DesignStrings.MigrationNameRequired);
        }

        var invalidPathChars = Path.GetInvalidFileNameChars();
        if (name.Any(c => invalidPathChars.Contains(c)))
        {
            throw new OperationException(
                DesignStrings.BadMigrationName(name, string.Join("','", invalidPathChars)));
        }

        var contextClassName = context.GetType().Name;
        if (string.Equals(name, contextClassName, StringComparison.Ordinal))
        {
            throw new OperationException(
                DesignStrings.ConflictingContextAndMigrationName(name));
        }

        var services = _servicesBuilder.Build(context);
        EnsureServices(services);

View on GitHub (pinned to dbf9771522)

Solutions

1. Supply a meaningful PascalCase name, e.g. 'AddOrderStatus'.
2. Validate/guard the name variable in your script before invoking the command.
3. If calling the API, default to a generated name derived from the change.

Example fix

// before
dotnet ef migrations add ""
// after
dotnet ef migrations add AddOrderStatus

if (string.IsNullOrWhiteSpace(migrationName)) throw new ArgumentException("A migration name is required.");

static bool IsValidMigrationName(string? n) => !string.IsNullOrWhiteSpace(n);

When it happens

Trigger: Calling dotnet ef migrations add with no argument, or AddMigration(name: "") / AddMigration(name: null) via the API. string.IsNullOrWhiteSpace(name) is true.

Common situations: Scripting the CLI and forgetting to interpolate the name; invoking the API programmatically with a computed name that came back empty; tooling that prompts for a name and got an empty response.

Related errors

• The migration name '{name}' is not valid. Migration names ca
• The name you have chosen for the migration, '{name}', is the
• No DbContext named '{name}' was found.
• The wildcard '*' can only be used with commands that run for
• No DbContext was found in assembly '{assembly}'. Ensure that

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/ca44009556517e11. Report an issue: GitHub.