Reportviewer :Method not found: 'System.String System.String.Format(System.IFormatProvider, System.String, System.Object)'.

Question

i'm getting below Error while loading Report

Method not found: 'System.String System.String.Format(System.IFormatProvider, System.String, System.Object)'.

Answer 1

Hi @Kedar Bhapkar ,
According to its MSDN page,
https://learn.microsoft.com/en-us/dotnet/api/system.string.format?redirectedfrom=MSDN&view=net-7.0#System_String_Format_System_IFormatProvider_System_String_System_Object_
the overload you're using is only supported on .NET 4.6.
Either configure the host to run .NET 4.6 or change the target framework of the project to 4.5 and recompile.
In 4.5 there's a params object[] overload which will then be chosen, without having to alter your code.
https://learn.microsoft.com/en-us/dotnet/api/system.string.format?redirectedfrom=MSDN&view=netframework-4.5#System_String_Format_System_IFormatProvider_System_String_System_Object_
If you can neither upgrade host to 4.6 nor downgrade project to 4.5 there is a workaround : pass an "object[]" as args instead of an "object".
So you will force usage of the "params object[]" overload. Example :
return string.Format(formatProvider, "{0:" + format + "}", new object[] { value });
Best regards,
Lan Huang

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