dotnet/efcore · error · OperationException

No ModelSnapshot was found.

Error message

No ModelSnapshot was found.

What it means

`RemoveMigration` reads `Dependencies.MigrationsAssembly.ModelSnapshot`; when that property is `null` (no class deriving from `ModelSnapshot` is present in the migrations assembly) it throws `OperationException(NoSnapshot)`. The snapshot is what `RemoveMigration` rewrites to roll the model back, so without it the operation cannot proceed.

Source

Thrown at src/EFCore.Design/Migrations/Design/MigrationsScaffolder.cs:256

    /// <param name="force">Revert the migration if it has been applied to the database.</param>
    /// <param name="language">The project's language.</param>
    /// <param name="dryRun">If <see langword="true" />, then nothing is actually written to disk.</param>
    /// <param name="offline">Remove the migration without connecting to the database.</param>
    /// <returns>The removed migration files.</returns>
    public virtual MigrationFiles RemoveMigration(
        string projectDir,
        string? rootNamespace,
        bool force,
        string? language,
        bool dryRun = false,
        bool offline = false)
    {
        var files = new MigrationFiles();

        var modelSnapshot = Dependencies.MigrationsAssembly.ModelSnapshot;
        if (modelSnapshot == null)
        {
            throw new OperationException(DesignStrings.NoSnapshot);
        }

        var codeGenerator = Dependencies.MigrationsCodeGeneratorSelector.Select(language);

        IModel? model = null;
        var migrations = Dependencies.MigrationsAssembly.Migrations
            .Select(m => Dependencies.MigrationsAssembly.CreateMigration(m.Value, _activeProvider))
            .ToList();
        if (migrations.Count != 0)
        {
            var migration = migrations[^1];
            model = Dependencies.SnapshotModelProcessor.Process(migration.TargetModel);

            if (!Dependencies.MigrationsModelDiffer.HasDifferences(
                    model.GetRelationalModel(),
                    Dependencies.SnapshotModelProcessor.Process(modelSnapshot.Model, resetVersion: true).GetRelationalModel()))
            {
                var applied = false;

View on GitHub (pinned to dbf9771522)

Solutions

1. Re-add a migration (`dotnet ef migrations add <Name>`) to regenerate the snapshot, then retry the remove.
2. Check that `MigrationsAssembly` is configured to the assembly that actually holds your migration classes.
3. Restore the deleted `*ModelSnapshot.cs` from source control.

Example fix

// before
dotnet ef migrations remove   // no ModelSnapshot present
// after
dotnet ef migrations add RestoreSnapshot   // regenerates ModelSnapshot
dotnet ef migrations remove

// Ensure a ModelSnapshot exists before calling RemoveMigration.
var migrationsAssembly = serviceProvider
    .GetRequiredService<Microsoft.EntityFrameworkCore.Migrations.IMigrationsAssembly>();
if (migrationsAssembly.ModelSnapshot is null)
    throw new InvalidOperationException(
        "No ModelSnapshot found. Re-add a migration to regenerate it before removing.");

scaffolder.RemoveMigration(projectDir, rootNamespace, force: false);

When it happens

Trigger: `dotnet ef migrations remove` (or `MigrationsScaffolder.RemoveMigration(...)`) when the migrations assembly contains no `*ModelSnapshot` class — e.g. the snapshot file was manually deleted, the project was set up without ever producing one, or `MigrationsAssembly` points at the wrong assembly.

Common situations: Manually deleting `*ModelSnapshot.cs`, source-control conflicts that dropped the snapshot, a misconfigured `options.UseXxx(...).MigrationsAssembly(typeof(...).Assembly.FullName)` pointing somewhere with no snapshot, or removing migrations until none remain and then removing once more.

Related errors

• Changes have been made to the model since the last migration
• You cannot add a migration with the name 'Migration'.
• The name '{migrationName}' is used by an existing migration.
• The migration '{name}' has already been applied to the datab
• No DbContext named '{name}' was found.

AI-assisted analysis of dotnet/efcore@dbf9771522 (2026-08-06). Data as JSON: /api/errors/2d354998bf0a294f. Report an issue: GitHub.