Help with a Dependency Register issue

Hi, I am working on an upgrade of nop commerce and when we try to build it on a new server we are seeing the below issue and the older version has no problem. Can anyone please provide with any help?
CoreCLR Version: 5.0.1221.52207

.NET Version: 5.0.12

Description: The process was terminated due to an unhandled exception.

Exception Info: System.TypeLoadException: Method 'Register' in type 'Nop.Plugin.Tax.AvalaraTax.AvalaraTaxDependencyRegistrar' from assembly 'Nop.Plugin.Tax.AvalaraTax, Version=2.5.1.0, Culture=neutral, PublicKeyToken=null' does not have an implementation.

   at System.Reflection.RuntimeAssembly.GetExportedTypes()

   at FluentValidation.AssemblyScanner.FindValidatorsInAssembly(Assembly assembly) in C:\Projects\FluentValidation\src\FluentValidation\AssemblyScanner.cs:line 46

   at FluentValidation.ServiceCollectionExtensions.AddValidatorsFromAssembly(IServiceCollection services, Assembly assembly, ServiceLifetime lifetime, Func`2 filter) in

Which nopCommerce version you are trying to upgrade into?
Assuming nopCommerce 4.40
I would request you take the default Nop.Plugin.Tax.Avalara plugin of 4.40.4 version and replace it with existing one and try again.