Visual Studio 2013 中的“您是否缺少 using 指令或程序集引用”

Question

Good Day everyone. I'm developing a Cross Platform Application in Xamarin.Forms when I encounter this error "Are you missing a using directive or an assembly reference". My project is working fine before I install a Nuget package (Circle Image View in Xamarin), but when I uninstall it (without changing a single line of code) the said error started to appear. I tried to Build, Rebuild it but still it does not work. Anything I can do to fix this? Any help will be appreciated. Thanks a lot.

These are the errors:

Error 1:

The type or namespace name 'Xamarin' could not be found (are you missing a using directive or an assembly reference?)

Error 2:

The type or namespace name 'Application' could not be found (are you missing a using directive or an assembly reference?)

Error 3:

The type or namespace name 'Xamarin' could not be found (are you missing a using directive or an assembly reference?)

Error 4:

The type or namespace name 'ContentPage' could not be found (are you missing a using directive or an assembly reference?)

Answer 1

When I got an error like this on my Environment, I do following:

1. Clean solution in VisualStudio
2. Close VisualStudio
3. Delete all "bin" and "obj" Folders (from the whole solution) manually
4. Delete "packages" Folder manually
5. Restart VisualStudio
6. Rebuild all

In most cases, this solves this reference-problems (in my case)

Answer 2

It sounds like you're missing your Xamarin.Forms packages.

Can you expand your Packages directory in the Solution Explorer, and see if it's in there?

---

Try this :

1. Select the project in the Solution tab
2. Select Project along the top menu
3. Select Add Nuget Packages ...
4. Do a search for Xamarin.forms
5. Add Xamarin.forms to that project

Answer 3

• Right click on the referenced project -> Unload Project
• Right click on the referenced project -> Edit ...
• Add a space after any line in the file
• Save
• Right click on the referenced project -> Reload Project

Answer 4

What is the nuget package that you uninstall? Are you sure you aren't using anywhere in the code. If there are any references to it you will get this error.

For example if you have:

using Ninject;

And then you uninstall ninject you would get this error.

Answer 5

这发生在我身上，我的问题是我将 dll 编译为比我添加引用的项目更新的 .net 框架版本。

Answer 6

For me, it helped to add this line to my *.csproj:

<Reference Include="...">
    <SpecificVersion>False</SpecificVersion>
</Reference>

Answer 7

I just quit Visual Studio and started it again. The error was gone!

Answer 8

As well as deletion of bin and packages folders manually, deleting the respective error from the test.Android.csproj file worked for me. The error was

this project references nuget package(s) that are missing on this computer

Answer 9

My case was very weird. I suddenly started getting this for just one file for no reason at all.

After deleting and retyping the using directives, the error was gone.