Namespace references keep breaking in Visual Studio

Question

Since updating Unity from 2019.2 to 2019.3, I am unable to compile the project code in Visual Studio. It still compiles and runs in the Unity Editor but Visual Studio gives hundreds of missing reference errors ("The type or namespace name 'XXX' could not be found (are you missing a using directive or an assembly reference?)"). This includes files which I wrote, i.e. my own created namespaces.

Nothing I've tried works (see below) except for one thing. If I manually remove the references to all four assemblies in visual studio and re-add them, the solution will compile. But when I then close VS and reopen the same error comes up.

The assemblies are Assembly-CSharp, Assembly-CSharp-Editor, Assembly-CSharp-Editor-firstpass and Assembly-CSharp-firstpass. The normal ones that get created as far as I know.

Why does the reference break each time I restart VS? (Edit: and sometimes when rebuilding the solution without restarting)

Versions

Unity 2019.3.12f1 Personal.

Visual Studio Community 2017 15.9.22.

I've tried:

all of these https://stackoverflow.com/questions/29962432/visual-studio-refuses-to-build-project-due-to-missing-assembly-reference-that-is
all of these https://stackoverflow.com/questions/450999/are-you-missing-an-assembly-reference-compile-error-visual-studio
All of these http://www.codeandyou.com/2017/08/missing-assembly-reference-in-visual.html
Removing the .vs folder and all VS files from the Unity project folder and letting the editor regenerate them. Also regenerated manually from within unity
- Making sure Visual Studio (and the Visual Studio Tools for Unity (which is installed using the Visual Studio installer)) are fully up to date.
- Updated VS to the latest version
Removed VS Code package (I'm not using Code) from Unity, then readded.
A number of restarts of Unity and VS in between all the above.

Edit:

From more testing I found that now and then (don't know what triggers it) the reference will break without closing Visual Studio

Answer 1

Best Answer

Answer by IINovaII · May 13, 2020 at 08:15 AM

It's a bug that happens in Unity 2019.3.12f. Try the newer Unity version 2019.3.13 instead. It's been fixed there. - Nova

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D3Duck · May 13, 2020 at 09:27 AM 0

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Wow. I hit check for updates in the editor and it told me there were none... But found it in the hub. Downloading it now

D3Duck · May 13, 2020 at 10:43 AM 0

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If I had a million dollars I'd give it to you. I spent 8+ hours trying to figure this out thinking Unity was up to date... It's working now

IINovaII D3Duck · May 13, 2020 at 12:32 PM 0

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I'm happy that I was able to help you. - Nova

Answer 2

Answer by luixodev · Sep 05, 2020 at 10:24 AM

Same here when I update to Unity 2020.1.4f.4412, any idea?

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luixodev · Sep 05, 2020 at 12:02 PM 13

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Close VS, then create a new c# file inside unity, double click the file, then all namespaces were restored.

Ville907 luixodev · Nov 24, 2020 at 10:12 PM 1

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This worked for me! Thanks ;)

alexis78963_unity luixodev · May 07, 2021 at 10:27 AM 0

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Awesome thanks!

ComeSweetDeath luixodev · May 21, 2021 at 04:59 AM 0

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Thank you, that was magic

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SkillcraftHD · Jul 28, 2021 at 12:49 PM 0

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hey, yeah it works always but my problem is that the problem always occurs again and again randomly

Answer 3

Answer by metixgosu · Apr 08, 2021 at 12:13 AM

Trigger is if you remove mononehaviour if from any script what is attached on game object in unity, if you want remove mono for any reason in vs just remove it from game object first

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Answer 4

Answer by HyronXIII · Sep 01, 2021 at 02:45 PM

Also closing VS and from the Editor clicking Assets -> Open C# Project worked for me, which I assume does something similar to the above mentioned creating a new C# script

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Answer 5

Answer by zwang-steven · Oct 12, 2021 at 04:13 PM

Regenerate project files fixes the issue:

Go to Unity 【Edit】 → 【Preferences】 → 【External Tools】 → Click the 【Regenerate project files】 button under "Generate .csproj files for:" → Back to VS

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Namespace references keep breaking in Visual Studio

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I've tried:

Edit:

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