[unity3d daily bug] unity3d solves "the type or namespace name" XXX "cannot be found (are you missing the using directive or assembly reference?)" Etc

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Hello everyone , I'm a Buddhist Engineer * Quiet little magic dragon *, Update from time to time Unity Development skills , I think it's useful. Remember to press one button three times .

One 、 Preface

First , See if it's similar to me ：

Problem with missing namespace references .

Similar problems are ：

The type or namespace name `MySql’ could not be found. Are you missing an assembly referen

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

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

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

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

UP It's from Visual Studio Of NuGet A set of plug-ins installed directly by the package manager , stay Visual Studio There is no wrong report , But in Unity China will report an error .

Two 、 Cause analysis

The main reasons are as follows ：

1、Unity Version issue for , The old version cannot support the new dependent Library .
2、Unity The target framework library of does not support .Net Framework library for
3、Unity This is not included in dll

3、 ... and 、 solve the problem

It's easy to solve the problem when you know it .

3-1、Unity Version of the problem

If it is Unity The version problem is to upgrade the version

3-2、Unity The target framework library is not supported

If it is Unity The target framework library of does not support .Net Framework library for .

stay Unity Editor , Click on File→Build Settings→Player find Api Compatibility Level：

take .NET Standard 2.0 Change to .NET 4.x.

install .NET 4.6 Framework of the , You can change to 4.6.

3-3、Unity No import dll

There are children's shoes that can say ： I Unity Target framework library 、Unity There is no problem with the version of , But what about reporting errors .

Then find the corresponding assembly according to the missing assembly dll file , Then put Unity Of Plugins In the folder ：

For example, I lack JWT and Newtonsoft Assembly of , I found the corresponding dll file ：

Put it in Unity Of Plugins In the folder ：

Wait until the compilation is complete , The error report disappears .

as for dll Where can I find the documents ... To be honest, I don't have a good way , Baidu .. Or go github look for , Students who have better methods can also leave a message to tell me .