If a Unity Project needs access to a part of the .NET class library API that is not compiled by default, the Project can inform the C# compiler in Unity. The behavior depends which .NET profile the Project uses.
If your Projects use the .NET Standard 2.0 Api Compatibility Level, you shouldn’t need to take any additional steps to use part of the .NET class library API. If part of the API seems to be missing, it might not be included with .NET Standard 2.0. The Project may need to use the .NET 4.x Api Compatibility Level instead.
By default, Unity references the following assemblies when using the .NET 4.x Api Compatibility Level:
You should reference any other class library assemblies using an csc.rsp file. You can add this file to the AssetsAny media or data that can be used in your game or Project. An asset may come from a file created outside of Unity, such as a 3D model, an audio file or an image. You can also create some asset types in Unity, such as an Animator Controller, an Audio Mixer or a Render Texture. More info
See in Glossary directory of a Unity Project, and use it to pass additional command line arguments to the C# compiler. For example, if a Project uses the HttpClient
class, which is defined in the System.Net.Http.dll assembly, the C# compiler might produce this initial error message:
The type `HttpClient` is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Net.Http, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'.
You can resolve this error by adding the following csc.rsp file to the Project:
-r:System.Net.Http.dll
You should reference class library assemblies as described in the example above. Don’t copy them into the Project directory.
Exercise caution when using an csc.rsp file to reference class library assemblies. If you change the Api Compatibility Level from .NET 4.x to .NET Standard 2.0, and an csc.rsp like the one in the example above exists in the Project, then C# compilation fails. The System.Net.Http.dll assembly does not exist in the .NET Standard 2.0 profile, so the C# compiler is unable to locate it.
The csc.rsp file can have parts that are specific to the current .NET profile. If you make changes to the profile, you need to modify the csc.rsp file.
Did you find this page useful? Please give it a rating:
Thanks for rating this page!
What kind of problem would you like to report?
Is something described here not working as you expect it to? It might be a Known Issue. Please check with the Issue Tracker at issuetracker.unity3d.com.
Thanks for letting us know! This page has been marked for review based on your feedback.
If you have time, you can provide more information to help us fix the problem faster.
Provide more information
You've told us this page needs code samples. If you'd like to help us further, you could provide a code sample, or tell us about what kind of code sample you'd like to see:
You've told us there are code samples on this page which don't work. If you know how to fix it, or have something better we could use instead, please let us know:
You've told us there is information missing from this page. Please tell us more about what's missing:
You've told us there is incorrect information on this page. If you know what we should change to make it correct, please tell us:
You've told us this page has unclear or confusing information. Please tell us more about what you found unclear or confusing, or let us know how we could make it clearer:
You've told us there is a spelling or grammar error on this page. Please tell us what's wrong:
You've told us this page has a problem. Please tell us more about what's wrong:
Thanks for helping to make the Unity documentation better!
When you visit any website, it may store or retrieve information on your browser, mostly in the form of cookies. This information might be about you, your preferences or your device and is mostly used to make the site work as you expect it to. The information does not usually directly identify you, but it can give you a more personalized web experience. Because we respect your right to privacy, you can choose not to allow some types of cookies. Click on the different category headings to find out more and change our default settings. However, blocking some types of cookies may impact your experience of the site and the services we are able to offer.
More information
These cookies enable the website to provide enhanced functionality and personalisation. They may be set by us or by third party providers whose services we have added to our pages. If you do not allow these cookies then some or all of these services may not function properly.
These cookies allow us to count visits and traffic sources so we can measure and improve the performance of our site. They help us to know which pages are the most and least popular and see how visitors move around the site. All information these cookies collect is aggregated and therefore anonymous. If you do not allow these cookies we will not know when you have visited our site, and will not be able to monitor its performance.
These cookies may be set through our site by our advertising partners. They may be used by those companies to build a profile of your interests and show you relevant adverts on other sites. They do not store directly personal information, but are based on uniquely identifying your browser and internet device. If you do not allow these cookies, you will experience less targeted advertising. Some 3rd party video providers do not allow video views without targeting cookies. If you are experiencing difficulty viewing a video, you will need to set your cookie preferences for targeting to yes if you wish to view videos from these providers. Unity does not control this.
These cookies are necessary for the website to function and cannot be switched off in our systems. They are usually only set in response to actions made by you which amount to a request for services, such as setting your privacy preferences, logging in or filling in forms. You can set your browser to block or alert you about these cookies, but some parts of the site will not then work. These cookies do not store any personally identifiable information.