Decimal to date

Hello pcolas 

please share you M-code. This error is maybe caused from a wrongly applied column transformation or pivoting function (function that doesn't work with data type. Here an approach how you can force a data transformation by culture

let
    Quelle = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WKkktLjFU0lGKik8uLS7JzwUyDc30DSz0jQwMTRVMrAwMlGJjAQ==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [#"Header handle" = _t, #"Event type" = _t, #"UTC start" = _t]),
    ToDateTime = Table.TransformColumns
    (
        Quelle,
        {
            {
                "UTC start",
                each DateTime.FromText(_,"it-IT"),
                type datetime
            }
        }
    ),
    Pivot = Table.Pivot(ToDateTime, List.Distinct(ToDateTime[#"Event type"]), "Event type", "UTC start", List.Max)
in
    Pivot

Copy paste this code to the advanced editor in a new blank query to see how the solution works. If this solution fits your need, copy and past a part of it and implement it in your query

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Kudoes are nice too

Have fun

Jimmy