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Missing Namespace UI error appears when a script tried to use UnityEngine.UI



After running through a few packages in the Assets Store, loading and unloading packages and DLLs, I got into a state with my project when Unity doesn't recognise "using UnityEditor.UI" in all the scripts in the Google Cloud Vision project.

This does not happen when i freshly install the Google Cloud Vision asset in a fresh new project.

To reproduce the error in the console:
- download this project
- open it with Unity 2019.2.0b3 or 2019.3.0a3 on Windows 10
- notice the compilation errors:
Assets\FrostweepGames\GCSpeechRecognition\Examples\Example\Example.cs(4,19): error CS0234: The type or namespace name 'UI' does not exist in the namespace 'UnityEngine' (are you missing an assembly reference?)

Reproduced with Unity 2019.2.0b3 and 2019.2.0a3
Cannot reproduce in Unity 2019.1.0f2, 2019.3.0a2, 2019.2.0a14

Comments (64)

  1. abcd8197

    Jan 11, 2022 14:13

    First of all, I'm sorry that my English is immature.

    I am using visual studio 2019.

    It was resolved because you right-clicked on the top of 'Solution Explorer' and loaded all projects.

    I hope people like me can solve their problems.

    I used a translator.

  2. ZakaDjeb

    Nov 17, 2020 12:55

    Try adjusting the settings to the following;
    Edit -> Project settings -> Player -> Api Compatability Level* -> .NET Standard 2.0

  3. Ashwini03

    Oct 20, 2020 12:35

    Hello.. I have tried everything following your suggestions But worked one thing. In my project one folder was there "text mesh pro". After deleting that the issue solved.

  4. pauliuso

    Sep 10, 2020 10:41

    For me the problem was that I used several SDK's from Google, and so it happened that my project got several same .dlls so I had to delete folder "PackageCache" from "Library" and then the error dissapeared.

  5. ImperialDynamics

    Jul 15, 2020 09:30

    BENFC1993 you are my hero! I love you!
    I had tried everything (and i mean everything) from every forum out there. Nothing worked. I was pulling my hair out. BENFC1993's solution works guys and ladies. I'll repeat it here:

    All you need to do to fix this is got to Edit > Preferences > External Tools make sure the 'Generate all .csproj files.' is checked the in your IDE delete the:


    files in the root of your project.

    Close and reopen vscode.

  6. De-Panther

    Jul 11, 2020 17:47

    Using 2019.3, my project folder was missing "Assembly-CSharp-Editor.csproj" file. Creating dummy script that uses UnityEditor, made Unity to generate this file, and that solved the issue.

  7. YodaOnNutella

    Jul 05, 2020 12:17

    Thank you BENFC1993!!!
    amazing, also got rid of 203 errors in log lol

  8. AntonAmpli

    May 25, 2020 14:23

    This issue is still present and the workaround provided in the comment does not work for every one. 2019.3.11.f1

  9. Plysovej_Kaktus

    May 19, 2020 18:30

    BENFC1993 Thank you!!!

  10. donnmatch98

    May 17, 2020 20:42

    Issue still a problem, unityengine.ui not showing up

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