The namespace "" does not exist or the namespace name is resolved

1. There is indeed no reference to the prompt namespace; (this class is a cainiao-level problem. Generally, you can add the reference and compile it ;)

2. References are added and compilation fails. (This type of problem has never been encountered before. Net 2 and is a new specialty after 3 ;)

 

The root cause of this problem is that the. Net of the Project selects the client profile version. Client Profile Introduction

Because client profile is a simplified framework version, there are many restrictions when using it. For example, system. Web is missing when adding a reference;

. Net full version

 

. Net Client Version

 

 

If you encounter the same problem, check the. NET version first. If the referenced target project is. Net full and the local project is. Net client, the compilation failure is prompted when the reference is explicitly added;

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