Why should you care?

ShopNest support ticket "checkout failed" needs dev to read DbUpdateException inner SqlException 2627 unique SKU not generic 500.

See it live — copy this example

Paste into a .NET project with EF Core packages, then run with LocalDB/SQL Server (dotnet ef / dotnet run).

try
{
    await _context.SaveChangesAsync(ct);
}
catch (DbUpdateException ex)
{
    _logger.LogError(ex, "Save failed. Entries: {Entries}",
        string.Join(", ", ex.Entries.Select(e => e.Entity.GetType().Name)));

    if (ex.InnerException is SqlException sql)
        _logger.LogError("SQL {Number}: {Message}", sql.Number, sql.Message);
    throw;
}

What happened?

• ex.Entries lists entities involved in failure.
• SqlException.Number 2627 is unique violation; 547 is FK violation — map to user messages.

Practice next

1. Log full exception chain server-side always.
2. Reproduce with SQL Profiler capturing failing batch.
3. Use entries collection to identify which entity failed validation.
4. Build exception mapper dictionary for ShopNest support portal codes.
5. Simulate timeout with low CommandTimeout and catch SqlException -2.

Remember

DbUpdateException wraps SQL errors. Log entries and SqlException number. Map common numbers to business messages.

ShopNest duplicate SKU incident

Logs show SqlException 2627 on Products.Sku during seller bulk upload.

Outcome: Support tells seller exact SKU conflict instead of generic error.