Fixing Visual Studio’s IntelliSense (auto-complete) in Unity

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One of the biggest perks of using Microsoft’s Visual Studio to write your Unity scripts is IntelliSense — a code completion aid in Visual Studio that offers suggestions as you write your code, and contextually presents you with information about classes, properties and methods that you are working with.

Given Unity’s enormous scripting API, IntelliSense is a tremendously helpful feature, especially for coders who are beginning their foray into developing games and software with Unity; and while we’d love to say that IntelliSense is automatically set up and linked to Unity’s API when you install it with the Unity Editor, sometimes that’s just not the case. So, if you’ve got both Unity and Visual Studio set up, but find that IntelliSense is still not offering Unity API suggestions, then this guide is for you.

There can be many reasons why IntelliSense is failing to work properly on your device, and we are assuming that you’ve already scoured the Internet a fair bit before stumbling on our article. Hence, we’ve put together a table of contents of sorts below, so if you’ve already tried some of the solutions we have, you can skip right through them.

If you prefer watching a video instead of reading, do check out our video guide for this post too.

1. Is my IntelliSense not working?
2. Getting IntelliSense working
   1. Open your scripts from Unity
   2. Setting Unity’s External Script Editor
   3. Visual Studio Tools for Unity
   4. Check your .NET API compatibility level
   5. Check if the Assembly-Csharp solution is loaded
   6. Regenerating your Unity project files
3. Conclusion
4. Video guide

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1. Is my IntelliSense not working?

For IntelliSense to detect and work with Unity’s API, Visual Studio needs to:

1. Be linked to the Unity Editor, and;
2. Have the appropriate extensions installed (read further to find out what they are)

If you’ve installed Visual Studio via Unity Hub, this can have been automatically set up, but not always. Due to the bevy of ways which you can install Unity and Visual Studio, misconfigurations can happen, and you might end up with Visual Studio not integrating itself into Unity, and an IntelliSense feature that is not properly linked to Unity’s API.

We’ve found that, when installing some versions of Unity 2019 and 2020, Visual Studio does not always integrate with Unity’s API by default. So if things are not working properly, it might not be caused by misconfiguration on your end.

To check if IntelliSense is properly set up, open any script from the Unity Editor, and look out for 2 things:

1. Whether the top-left dropdown says Miscellaneous Files. If it does, then IntelliSense is not set up (it has to say Assembly-Csharp.
2. Try declaring a Unity variable, like a GameObject. If IntelliSense is properly set up, Visual Studio should have an auto-complete suggestion for you before you finish typing.

2. Getting IntelliSense working

So if IntelliSense isn’t working for you, what should you do?

a. Open your scripts from Unity

Before you try anything else from here, first make sure that your scripts are opened from within Unity, i.e. whenever you want to edit your scripts, double-click on them in the Unity Editor so that Visual Studio is opened by Unity.

If IntelliSense still doesn’t work when you do this, then continue onto the steps below:

b. Setting Unity’s External Script Editor

From the Unity Editor, access the Preferences window from Edit > Preferences. Then, click on 1) the External Tools tab.

Set 2) the External Script Editor to the version of Visual Studio that you installed alongside Unity, then click on 3) the Regenerate project files button (if it’s there).

Once that’s done, restart Visual Studio and see if IntelliSense now works. If it still doesn’t, then you might be missing…

If Visual Studio doesn’t appear on the dropdown, you will have to use the Browse… option (pictured above) to find it. It’s typically under C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\Common7\IDE\devenv.exe for Windows devices.

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c. Visual Studio Tools for Unity

To install this, open Visual Studio and go to Tools > Get Tools and Features.

Note: You’ll need administrator permissions to open this window, as it makes changes to the Visual Studio installation on your computer.

Once the installer is open, go to Workloads and find Game development with Unity. Check the box, and then click on the Modify button on the bottom-right corner to begin installation.

A popup may ask you to close certain processes before beginning installation. If this happens, close your Visual Studio project and the Unity Editor application.

When installation completes, restart both Unity and Visual Studio, then check to see if IntelliSense now works.

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d. Check your .NET API compatibility level

If IntelliSense still refuses to work, you can open the Unity Editor and head to Edit > Project Settings and access the Player (or Player Settings) tab. Scroll down to the Other Settings sub-tab, and find the Api Compatibility Level dropdown under the Configuration heading.

You want to set the Api Compatibility Level to a different option, and see which is the one that works for your device.

e. Check if the Assembly-Csharp solution is loaded

If you have tried all of the above steps, but your Intellisense still doesn’t work, then it may be because you have accidentally unloaded the solution (i.e. what Visual Studio calls their project setting files) for your project. To check if that is the case:

1. In Visual Studio, go to View > Solution Explorer.
2. The Solution window should pop up by the side of Visual Studio. Check if there is a tab that says Assembly-Csharp (unloaded). If there isn’t, you likely have not set your external script editor, or downloaded Visual Studio Tools for Unity.
3. Right-click on Assembly-Csharp (unloaded) and select Reload project. The dropdown on the top left corner of Visual Studio should change from Miscellaneous Files to Assembly-Csharp. If that happens, congratulations! IntelliSense should now be working.
4. If (3) fails, close Visual Studio and reopen it again.

Below is a GIF demonstrating the steps above.

f. Manually regenerating your Unity project files

If the above solutions we’ve proposed did not work for you, you can also try this solution from one of our comment contributions.

Note: Back up your Unity project before trying this, as we are deleting some essential project files and letting Unity regenerate them.

1. Close both Visual Studio and Unity on your device.
2. Remove all .sln and .csproj files in your Unity project folder.
3. Remove the .vs and Library folders in your Unity project folder.
4. Re-open the project in Unity, then go to Assets > Open C# Project to open Visual Studio.

3. Conclusion

As with the other articles on the blog, we’d love if you leave a comment below, especially if you:

1. Find any errors in this article, or;
2. Find an IntelliSense fix that is not listed in this article

Your comments will add on to the information that is already here, and help other future readers!

4. Video guide

Is this post not visual enough? Perhaps our video guide of this post can help.

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