Adding new MVC/Razor items fails throwing an error about hostpolicy.dll

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This article describes how to fix error “There was an error running the selected code generator: ‘Failed to load the dll from \bin\Debug\netcoreapp\win-x86\hostpolicy.dll, HRESULT: 0x800700C1 An error occurred while loading required library hostpolicy.dll'” when you’re adding a new scaffolded item (such as a Razor page or ASP.NET Core MVC Controller).

Description

Imagine this: You’re developing your run-of-the-mill, basic, everyday ASP.NET Core web application. You need to add a new scaffolded item – that is,

How to create a new scaffolded item in ASP.NET Core

This’ll result in an error somewhat like below:

There was an error running the selected code generator:
'Failed to load the dll from [projectpath]\bin\Debug\netcoreapp\win-x86\hostpolicy.dll, HRESULT: 0x800700C1

An error occurred while loading required library hostpolicy.dll from ...

Solution

We have, in fact, seen this one before! A different context, similar error – so we actually know how to fix it!

For the other post (about a similar error with EF Core), see the post below. Even though it describes a fix to an issue that arises when running Update-Database, the underlying error is in fact the same that causes the error “There was an error running the selected code generator: (HRESULT: 0x800700C1)” for us here.

Author
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Antti K. Koskela

Developer / Architect / Consultant at Koskila / Valo Solutions Ltd. / Norppandalotti Software Co / Alter - Experience Ideas Ltd.

Antti Koskela is a proud digital native nomadic millennial full stack developer (is that enough funny buzzwords? That's definitely enough funny buzzwords!), who works as a Solutions Architect for Valo Intranet, the product that will make you fall in love with your intranet.

He's been a developer from 2004 (starting with PHP and Java), and he's been bending and twisting SharePoint into different shapes since MOSS. Nowadays he's not only working on SharePoint, but also on .NET projects, Azure, Office 365 and a lot of other stuff. He's also Microsoft MVP for Office Development.

This is his personal professional (e.g. professional, but definitely personal) blog.

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