Visual Studio deploys old version

In the Visual Studio Configuration Manager, Make sure either "AnyCPU" or "Mixed Platforms" is selected.  for "x86" option, some of the projects are not selected to compile (so you would get the old dlls).

If the compilation works in Debug Mode, the dlls should be generated at thee below folder .

NopCommerce\Presentation\Nop.Web\bin\Debug\netcoreapp3.1\

Delete the contents of this folder and build the code again to see the dlls are generated again.

If none of it works, copy the paste the build output log from visual studio.

Unfortunately I am not at home at the moment.
But to delete the dll's in the netcore2.2 folder wasn't succesfull.
They got built new, but the result was the same.


Another problem I have, is with the plugins. after a build(or rebuild) I often get the error "The Plugin "plugin name" system name is already defined, but this error I can easily solve.
Maybe there is a connection

I think they are connected.  I suspect that the code compilation is not happening completely.  

Post the log from Visual Studio output window, it should be straight forward to see which project is compiling and which project is not.

This is the outup from the build:

1>------ Build started: Project: Nop.Core, Configuration: Release Any CPU ------
1>C:\Program Files\dotnet\sdk\3.1.302\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.DefaultItems.targets(189,5): warning NETSDK1071: A PackageReference to 'Microsoft.AspNetCore.App' specified a Version of `2.2.5`. Specifying the version of this package is not recommended. For more information, see https://aka.ms/sdkimplicitrefs
1>Nop.Core -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Libraries\Nop.Core\bin\Release\netcoreapp2.2\Nop.Core.dll
1>Done building project "Nop.Core.csproj".
2>------ Build started: Project: Nop.Data, Configuration: Release Any CPU ------
2>Nop.Data -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Libraries\Nop.Data\bin\Release\netcoreapp2.2\Nop.Data.dll
3>------ Build started: Project: Nop.Services, Configuration: Release Any CPU ------
3>Nop.Services -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Libraries\Nop.Services\bin\Release\netcoreapp2.2\Nop.Services.dll
4>------ Build started: Project: Nop.Web.Framework, Configuration: Release Any CPU ------
5>------ Build started: Project: Nop.Tests, Configuration: Release Any CPU ------
6>------ Build started: Project: Nop.Plugin.ExchangeRate.EcbExchange, Configuration: Release Any CPU ------
5>Nop.Tests -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Tests\Nop.Tests\bin\Release\netcoreapp2.2\Nop.Tests.dll
7>------ Build started: Project: Nop.Services.Tests, Configuration: Release Any CPU ------
8>------ Build started: Project: Nop.Core.Tests, Configuration: Release Any CPU ------
7>Nop.Services.Tests -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Tests\Nop.Services.Tests\bin\Release\netcoreapp2.2\Nop.Services.Tests.dll
6>Nop.Plugin.ExchangeRate.EcbExchange -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\ExchangeRate.EcbExchange\Nop.Plugin.ExchangeRate.EcbExchange.dll
4>Nop.Web.Framework -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web.Framework\bin\Release\netcoreapp2.2\Nop.Web.Framework.dll
9>------ Build started: Project: Nop.Web, Configuration: Release Any CPU ------
10>------ Build started: Project: Nop.Plugin.Payments.Manual, Configuration: Release Any CPU ------
11>------ Build started: Project: Nop.Plugin.Shipping.UPS, Configuration: Release Any CPU ------
10>Nop.Plugin.Payments.Manual -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Payments.Manual\Nop.Plugin.Payments.Manual.dll
8>Nop.Core.Tests -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Tests\Nop.Core.Tests\bin\Release\netcoreapp2.2\Nop.Core.Tests.dll
12>------ Build started: Project: Nop.Plugin.Payments.CheckMoneyOrder, Configuration: Release Any CPU ------
13>------ Build started: Project: Nop.Plugin.Payments.PayPalStandard, Configuration: Release Any CPU ------
13>Nop.Plugin.Payments.PayPalStandard -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Payments.PayPalStandard\Nop.Plugin.Payments.PayPalStandard.dll
11>Nop.Plugin.Shipping.UPS -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Shipping.UPS\Nop.Plugin.Shipping.UPS.dll
14>------ Build started: Project: Nop.Plugin.Widgets.GoogleAnalytics, Configuration: Release Any CPU ------
12>Nop.Plugin.Payments.CheckMoneyOrder -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Payments.CheckMoneyOrder\Nop.Plugin.Payments.CheckMoneyOrder.dll
9>Nop.Web -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\bin\Release\netcoreapp2.2\Nop.Web.dll
15>------ Build started: Project: Nop.Plugin.ExternalAuth.Facebook, Configuration: Release Any CPU ------
16>------ Build started: Project: Nop.Plugin.Widgets.NivoSlider, Configuration: Release Any CPU ------
14>Nop.Plugin.Widgets.GoogleAnalytics -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Widgets.GoogleAnalytics\Nop.Plugin.Widgets.GoogleAnalytics.dll
16>Nop.Plugin.Widgets.NivoSlider -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Widgets.NivoSlider\Nop.Plugin.Widgets.NivoSlider.dll
15>Nop.Plugin.ExternalAuth.Facebook -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\ExternalAuth.Facebook\Nop.Plugin.ExternalAuth.Facebook.dll
17>------ Build started: Project: Nop.Web.MVC.Tests, Configuration: Release Any CPU ------
18>------ Build started: Project: Nop.Plugin.Pickup.PickupInStore, Configuration: Release Any CPU ------
19>------ Build started: Project: Nop.Plugin.Shipping.FixedByWeightByTotal, Configuration: Release Any CPU ------
17>Nop.Web.MVC.Tests -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Tests\Nop.Web.MVC.Tests\bin\Release\netcoreapp2.2\Nop.Web.MVC.Tests.dll
20>------ Build started: Project: Nop.Plugin.Tax.FixedOrByCountryStateZip, Configuration: Release Any CPU ------
21>------ Build started: Project: Nop.Plugin.DiscountRules.CustomerRoles, Configuration: Release Any CPU ------
18>Nop.Plugin.Pickup.PickupInStore -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Pickup.PickupInStore\Nop.Plugin.Pickup.PickupInStore.dll
21>Nop.Plugin.DiscountRules.CustomerRoles -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\DiscountRules.CustomerRoles\Nop.Plugin.DiscountRules.CustomerRoles.dll
20>Nop.Plugin.Tax.FixedOrByCountryStateZip -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Tax.FixedOrByCountryStateZip\Nop.Plugin.Tax.FixedOrByCountryStateZip.dll
19>Nop.Plugin.Shipping.FixedByWeightByTotal -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Shipping.FixedByWeightByTotal\Nop.Plugin.Shipping.FixedByWeightByTotal.dll
22>------ Build started: Project: Nop.Plugin.Payments.Square, Configuration: Release Any CPU ------
23>------ Build started: Project: Nop.Plugin.Payments.Qualpay, Configuration: Release Any CPU ------
24>------ Build started: Project: Nop.Plugin.Misc.SendinBlue, Configuration: Release Any CPU ------
25>------ Build started: Project: Nop.Plugin.Tax.Avalara, Configuration: Release Any CPU ------
24>Nop.Plugin.Misc.SendinBlue -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Misc.SendinBlue\Nop.Plugin.Misc.SendinBlue.dll
25>Nop.Plugin.Tax.Avalara -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Tax.Avalara\Nop.Plugin.Tax.Avalara.dll
23>Nop.Plugin.Payments.Qualpay -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Payments.Qualpay\Nop.Plugin.Payments.Qualpay.dll
22>Nop.Plugin.Payments.Square -> D:\Schule\Maturaprojekt_Kletterturm\Tests\nopCommerce\src\Presentation\Nop.Web\Plugins\Payments.Square\Nop.Plugin.Payments.Square.dll
========== Build: 25 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========


So I opened the website(local) and I got this error several times: An error occurred while starting the application.
Exception: A plugin with 'CurrencyExchange.ECB' system name is already defined
Nop.Web.Framework.Infrastructure.Extensions.ApplicationPartManagerExtensions.InitializePlugins(ApplicationPartManager applicationPartManager, NopConfig config) in ApplicationPartManagerExtensions.cs, line 475