dotnet/efcore · error · InvalidOperationException

The required column ' ' was not present in the results of a…

Error message

The required column '{column}' was not present in the results of a 'FromSql' operation.

What it means

Thrown by BufferedDataReader when a non-composed FromSqlRaw/FromSqlInterpolated query returns a result set that is missing at least one column the entity expects. EF looks up each expected column name in the reader's field-name map and reports the first one it cannot find.

Solutions

Make the raw SQL return every column the entity maps (including key, discriminator, and concurrency token columns).
Project into an anonymous/non-mapped DTO instead of an entity type to allow fewer columns.
Use SELECT * (or the specific full column list) so all mapped columns are present.
Verify column names in SQL match the mapped column names (case sensitivity depends on provider).

Example fix

// before
var users = dbContext.Users
    .FromSqlRaw("SELECT Id, Name FROM Users")
    .ToList(); // User also maps Email

// after
var users = dbContext.Users
    .FromSqlRaw("SELECT Id, Name, Email FROM Users")
    .ToList();

Defensive patterns

Strategy: validation

Validate before calling

static void EnsureFromSqlCoversColumns(IModel model, Type entityType, string sql, IReadOnlyList<string> readerColumns)
{
    var mapped = model.FindEntityType(entityType)!
        .GetProperties().Select(p => p.GetColumnName()).Where(n => n is not null).Cast<string>();
    foreach (var c in mapped)
        if (!readerColumns.Contains(c, StringComparer.OrdinalIgnoreCase))
            throw new InvalidOperationException($"FromSql result is missing mapped column '{c}'.");
}

Prevention

Return every mapped column from raw SQL (or use SELECT *).
Prefer LINQ over FromSql for entity materialization when possible.
Project into DTOs when only a subset of columns is needed.

When it happens

Trigger: context.Users.FromSqlRaw("SELECT Id, Name FROM Users") when the User entity also maps a property to column Email. InitializeFields detects FieldCount < _columns.Count and a missing column name.

Common situations: Raw SQL projection that omits a mapped column. Stored procedure that returns a subset of columns. Renaming a column in SQL but not the entity. Composite/TPH queries where a discriminator column is missing.

Related errors

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/eb3a4931581faf64. Report an issue: GitHub.

Appendix: source

Thrown at src/EFCore.Relational/Query/Internal/BufferedDataReader.cs:1241

                    index[_columnNames[i]] = i;
                }

                return index;
            }
        }

        private void InitializeFields()
        {
            var fieldCount = FieldCount;
            if (FieldCount < _columns.Count)
            {
                // Non-composed FromSql
                var readerColumns = _fieldNameLookup.Value;

                var firstMissingColumn = _columns.Select(c => c?.Name).FirstOrDefault(c => c != null && !readerColumns.ContainsKey(c));
                if (firstMissingColumn != null)
                {
                    throw new InvalidOperationException(RelationalStrings.FromSqlMissingColumn(firstMissingColumn));
                }

                throw new InvalidOperationException(RelationalStrings.TooFewReaderFields(_columns.Count, FieldCount));
            }

            _columnTypeCases = Enumerable.Repeat(TypeCase.Empty, fieldCount).ToArray();
            _ordinalToIndexMap = Enumerable.Repeat(-1, fieldCount).ToArray();
            if (_columns.Count > 0
                && _columns.Any(e => e?.Name != null))
            {
                // Non-Composed FromSql
                var readerColumns = _fieldNameLookup.Value;

                _indexMap = new int[_columns.Count];
                var newColumnMap = new ReaderColumn?[fieldCount];
                for (var i = 0; i < _columns.Count; i++)
                {
                    var column = _columns[i];

View on GitHub (pinned to 3a2006ef56)