Include MissingField Argument with Table.TransformColumnTypes Function for Power Query

user10456 It works in Power BI Desktop version 2.143.1378.0 (May 2025) and later, for Excel users it will depend on your O365 version/channel (confirmed on Current and M365 Monthly). Here's a sample you can try. 

let
    /* The July 2025 update to the documentation now mentions a MissingField type for Table.TransformColumnTypes */
    /* Here's sample data, a table with two columns: Date and Value */
    Source = #table(
        type table [Date = date, Value = number],
        {
            {#date(2024, 3, 12), 0.24368},
            {#date(2024, 5, 30), 0.03556},
            {#date(2023, 12, 14), 0.3834}
        }
    ),

    /* Attempt to change column types. */
    /* Note: "Customer ID" does not exist in the Source table, */
    /* so this step fails. */
    ChType_Default = Table.TransformColumnTypes(
        Source,
        {
            {"Date", type text}, 
            {"Customer ID", Int64.Type}, 
            {"Value", Percentage.Type}
        }
    ),

    /* Transform column types 3rd parameter accepts a Culture tag as text; "de-DE */
    /* Culture affects formatting/interpretation of values such as numbers and dates */
    ChType_Culture = Table.TransformColumnTypes(
        Source,
        {
            {"Date", type text}, 
            {"Value", Percentage.Type}
        },
        "de-DE"
    ),

    /* 3rd Parameter now also accepts a Record that may include a Culture and/ or MissingField. */
    /* MissingField.UseNull > Adds missing columns to the output containing null values. */
    /* In this case, "Customer ID" is added, filled with nulls. */
    ChType_RecordA = Table.TransformColumnTypes(
        Source,
        {
            {"Date", type text}, 
            {"Customer ID", Int64.Type}, 
            {"Value", Percentage.Type}
        },
        [Culture = "de-DE", MissingField = MissingField.UseNull]
    ),

    /* MissingField.Ignore > Ignores columns that don’t exist in the Source table, */
    /* preventing errors by skipping any missing columns. */
    ChType_RecordB = Table.TransformColumnTypes(
        Source,
        {
            {"Date", type text}, 
            {"Customer ID", Int64.Type}, 
            {"Value", Percentage.Type}
        },
        [Culture = "de-DE", MissingField = MissingField.Ignore]
    )
in
    ChType_RecordB