Message "DataFormatError"

[Mederic]

Hello,
I have a range named "Tab" with dates in columns,
After some transformations, if I change the column "Attribute" to date type, I have a column with errors.

How to correct the last step to transform this column in date ?
Thanks in advance
Regards

	janv-23	févr-23	mars-23	avr-23
Name	94	21	74	78
A	65	57	37	84
B	54	38	30	29
C	23	23	90	92
D	68	62	84	57

let
    Source = Excel.CurrentWorkbook(){[Name="Tab"]}[Content],
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", type any}, {"Column3", type any}, {"Column4", type any}, {"Column5", type any}}),
    #"Promoted Headers" = Table.PromoteHeaders(#"Changed Type", [PromoteAllScalars=true]),
    #"Unpivoted Other Columns" = Table.UnpivotOtherColumns(#"Promoted Headers", {"Column1"}, "Attribute", "Value"),
    #"Changed Type1" = Table.TransformColumnTypes(#"Unpivoted Other Columns",{{"Attribute", type date}})
in
    #"Changed Type1"

[Mederic]

Hello @AlienSx ,

Thank you for your message and sorry for the late reply.
I hadn't thought about the regional settings, indeed the 2 steps below work and solve the problem
thanks again

Regards

#"Changed Type with Locale" = Table.TransformColumnTypes(#"Unpivoted Other Columns", {{"Attribute", type datetime}}, "fr-FR"),
    #"Changed Type1" = Table.TransformColumnTypes(#"Changed Type with Locale",{{"Attribute", type date}})

[AlienSx · Accepted solution]

Hi, @Mederic . Feed Power Query with correct date representation in "MMM-yy" format. As far as I know in "fr-FR" locale the date must be like "janv.-23", not "janv-23" and so on.