dotnet/efcore · error · InvalidOperationException

' . ' and ' . ' are both mapped to column ' ' in ' ', but…

Error message

'{entityType1}.{property1}' and '{entityType2}.{property2}' are both mapped to column '{columnName}' in '{table}', but are configured to use different column orders ('{columnOrder1}' and '{columnOrder2}').

What it means

Two properties sharing a column declare different explicit column orders via HasColumnOrder. Since they share one physical column they must agree on its position; a mismatch would generate contradictory column-ordering in migrations. Compared as plain int? inequality (null = unspecified, treated as equal).

Solutions

Pass the same integer to HasColumnOrder on both properties.
Remove HasColumnOrder from one side so both leave it unspecified (null), letting conventions order them.
If the orders must differ, remap one property to its own column.

Example fix

// before
modelBuilder.Entity<User>().Property(u => u.Email).HasColumnOrder(3);
modelBuilder.Entity<UserSettings>().Property(s => s.Email).HasColumnOrder(5); // shared column

// after
modelBuilder.Entity<User>().Property(u => u.Email).HasColumnOrder(3);
modelBuilder.Entity<UserSettings>().Property(s => s.Email).HasColumnOrder(3);

Defensive patterns

Strategy: validation

Validate before calling

foreach (var (col, props) in sharedColumnGroups)
{
    var orders = props.Select(p => p.GetColumnOrder(storeObject)).Distinct().ToList();
    if (orders.Count > 1)
        Console.WriteLine($"Column {col} has conflicting orders: {string.Join(", ", orders)}");
}

Try / catch

try { _ = db.Model; } catch (InvalidOperationException ex) when (ex.Message.Contains("different column orders")) { // align HasColumnOrder on both properties, or remove it }

Prevention

Prefer leaving column order unset unless a specific schema ordering is required.
If set, define it in one place and reuse on all entities sharing the column.
Smoke-test the model at startup.

When it happens

Trigger: ValidateCompatible() reads property.GetColumnOrder(storeObject) and duplicateProperty.GetColumnOrder(storeObject); if the nullable ints differ it throws. Happens when both halves of a table-split call HasColumnOrder with different ordinals.

Common situations: Refactor that re-numbered columns on one entity but not its split partner; merging two separately-maintained models; scaffolded model edited to add column ordering on only one entity.

Related errors

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/0300a04333b10337. Report an issue: GitHub.

Appendix: source

Thrown at src/EFCore.Relational/Infrastructure/RelationalModelValidator.cs:1780

        if (!currentCollation.Equals(previousCollation, StringComparison.Ordinal))
        {
            throw new InvalidOperationException(
                RelationalStrings.DuplicateColumnNameCollationMismatch(
                    duplicateProperty.DeclaringType.DisplayName(),
                    duplicateProperty.Name,
                    property.DeclaringType.DisplayName(),
                    property.Name,
                    columnName,
                    storeObject.DisplayName(),
                    previousCollation,
                    currentCollation));
        }

        var currentColumnOrder = property.GetColumnOrder(storeObject);
        var previousColumnOrder = duplicateProperty.GetColumnOrder(storeObject);
        if (currentColumnOrder != previousColumnOrder)
        {
            throw new InvalidOperationException(
                RelationalStrings.DuplicateColumnNameOrderMismatch(
                    duplicateProperty.DeclaringType.DisplayName(),
                    duplicateProperty.Name,
                    property.DeclaringType.DisplayName(),
                    property.Name,
                    columnName,
                    storeObject.DisplayName(),
                    previousColumnOrder,
                    currentColumnOrder));
        }
    }

    /// <summary>
    ///     Returns the object that is used as the default value for the column the property is mapped to.
    /// </summary>
    /// <param name="property">The property to get the default value for.</param>
    /// <param name="storeObject">The identifier of the store object.</param>
    /// <returns>The object that is used as the default value for the column the property is mapped to.</returns>

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