String.Format(formatProvider, "{0:N}", value) regression

[BjornEngelen]

Running the code:

var formatProvider = CultureInfo.GetCultureInfo("nl-BE");
Console.WriteLine(String.Format(formatProvider, "{0:N}", 12.3456789m));
Console.WriteLine(String.Format(formatProvider, "{0:N}", 12345.6789m));

Will output for .NET Core 2.0 or 3.1 LTS:
12,35
12.345,68

Will output for .NET 5.0 or 6.0:
12,346
12.345,679

Is this intentional?

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

Tagging subscribers to this area: @tarekgh, @safern
See info in area-owners.md if you want to be subscribed.

Issue Details

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Running the code:

var formatProvider = CultureInfo.GetCultureInfo("nl-BE");
Console.WriteLine(String.Format(formatProvider, "{0:N}", 12.3456789m));
Console.WriteLine(String.Format(formatProvider, "{0:N}", 12345.6789m));

Will output for .NET Core 2.0 or 3.1 LTS:
12,35
12.345,68

Will output for .NET 5.0 or 6.0:
12,346
12.345,679

Is this intentional?

Author:	BjornEngelen
Assignees:	-
Labels:	area-System.Globalization, untriaged
Milestone:	-

[EgorBo]

#44587 (TLDR: in 5.0 .NET switched to ICU on Windows)

[tarekgh]

@BjornEngelen we have switched to use Unicode code standard CLDR data through the ICU library. We did that for .NET 5.0 and above. In general, globalization data is not stable and can change at any time. If you want to always have the old behavior (which format the number using 2 decimal digits, please use N2 instead.
I am closing this issue but feel free to send any follow-up questions and we'll be happy to help with. Thanks for your report.

Thanks @EgorBo for adding the link for other issue which has more discussions about that.