dotnet/efcore · error · InvalidOperationException

' ' cannot be set for ' ' at the same time as ' '. Remove…

Error message

'{conflictingConfiguration}' cannot be set for '{property}' at the same time as '{existingConfiguration}'. Remove one of these configurations.

What it means

A relational column may use exactly ONE server-generation strategy. This throw fires from StoreGenerationConvention.Validate when a property has both a DefaultValue and a DefaultValueSql set for the same StoreObjectIdentifier, because the provider cannot decide which one to render into the DDL/migration. EF treats these as mutually exclusive on a single column.

Solutions

Inspect the property named in the message and find both HasDefaultValue and HasDefaultValueSql calls across all configuration sources (fluent, attributes, scaffolded files, model snapshots).
Keep exactly one. If you want a literal CLR default, keep HasDefaultValue and delete HasDefaultValueSql; if you want a SQL expression (e.g. GETUTCDATE()), keep HasDefaultValueSql and delete HasDefaultValue.
Regenerate the migration so the column definition no longer emits both DEFAULT and the SQL expression.

Example fix

// before
modelBuilder.Entity<Order>()
    .Property(o => o.Created)
    .HasDefaultValue(DateTime.UtcNow)
    .HasDefaultValueSql("GETUTCDATE()");

// after
modelBuilder.Entity<Order>()
    .Property(o => o.Created)
    .HasDefaultValueSql("GETUTCDATE()");

Defensive patterns

Strategy: validation

Validate before calling

// Before configuring, ensure only one of the three is set for the store object
var prop = modelBuilder.Entity<Order>().Property(o => o.Created).Metadata;
var storeObj = StoreObjectIdentifier.Table("Orders");
if (prop.TryGetDefaultValue(storeObj, out _)
    && prop.GetDefaultValueSql(storeObj) is not null)
{
    throw new InvalidOperationException("Cannot set both DefaultValue and DefaultValueSql on Created.");
}

Prevention

Centralize each property's value-generation config in a single IEntityTypeConfiguration so two strategies cannot both be applied.
After scaffolding, audit any property that uses HasDefaultValue before adding HasDefaultValueSql.
Treat 'one of DefaultValue / DefaultValueSql / ComputedColumnSql per column' as a hard rule in code review.

When it happens

Trigger: Calling both HasDefaultValue(...) and HasDefaultValueSql(...) on the same property in OnModelCreating (or in an IEntityTypeConfiguration), possibly split across partial classes or scaffolded code plus a manual override. The convention runs during model finalization when the property is mapped to a table.

Common situations: Reverse-engineering a table that has a default SQL expression and then adding HasDefaultValue in fluent config; copy-pasting column setup between entities; upgrading an older model where only DefaultValueSql existed and a developer added DefaultValue for clarity.

Related errors

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/951f414b2cd78089. Report an issue: GitHub.

Appendix: source

Thrown at src/EFCore.Relational/Metadata/Conventions/StoreGenerationConvention.cs:132

                Validate(declaredProperty, declaringTable);
            }
        }
    }

    /// <summary>
    ///     Throws if there is conflicting store generation configuration for this property.
    /// </summary>
    /// <param name="property">The property to check.</param>
    /// <param name="storeObject">The identifier of the store object.</param>
    protected virtual void Validate(
        IConventionProperty property,
        in StoreObjectIdentifier storeObject)
    {
        if (property.TryGetDefaultValue(storeObject, out _))
        {
            if (property.GetDefaultValueSql(storeObject) != null)
            {
                throw new InvalidOperationException(
                    RelationalStrings.ConflictingColumnServerGeneration("DefaultValue", property.Name, "DefaultValueSql"));
            }

            if (property.GetComputedColumnSql(storeObject) != null)
            {
                throw new InvalidOperationException(
                    RelationalStrings.ConflictingColumnServerGeneration("DefaultValue", property.Name, "ComputedColumnSql"));
            }
        }
        else if (property.GetDefaultValueSql(storeObject) != null)
        {
            if (property.GetComputedColumnSql(storeObject) != null)
            {
                throw new InvalidOperationException(
                    RelationalStrings.ConflictingColumnServerGeneration("DefaultValueSql", property.Name, "ComputedColumnSql"));
            }
        }
    }

View on GitHub (pinned to 3a2006ef56)