The type or namespace name 'EventSystems' does not exist in the namespace 'UnityEngine' (are you missing an assembly reference?)

Archived Forums Questions & Answers
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ever since i updated from 2018 to 2019.3, i got errors like this, i don’t know how to work around or fix this issue, its driving me nuts.

3 Likes

can you show the code? how are ypu loading the library?

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5 Answers

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Thank’s for the reply’s but I found the answer on a discord server that help’s unity developer’s with error’s. I found out that In unity 2019.3ofa6 I had to re-inport “Unity UI” package in my asset’s folder. Somehow unity made it into a package and all I had to do was re-inport it. all the UI and event system stuff work’s. I had some problem’s with the nature kit asset’s, I reinstalled it from the store and it fixed up everything!! The game work’s perfectly now!..well sort of… just some terrain Messups now but I can fix it. Thank’s everyone.

I found the answer year's ago and didn't put it here, I found out that unity took all the assets I downloaded and put it in a separate file, along with my stuff too. So it read it like it didn't exist. So I imported the files from the assets tab (I had to really look) and was importing back all the stuff I needed to basically have my assets back. Unity never said this would happen. Took way too long to have an answer and to figure it out myself. I ended up finishing my project but thank you for the feedback :smiling_face:

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I know this is a year old but just to clarify steps if anyone else encounters this issue (as it’s just taken me some time to figure it out).

In the ‘Project’ pane in Unity editor > expand ‘Packages’ > right click ‘Unity UI’ > click ‘Reimport’ form the pop-up menu.

If anyone is interestested, this appears to be caused when importing certain packages from the asset store if they use a different project configuration. Not sure why exactly, however this method seems to fix things nicely.

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Just had this issue April of 2025 on Unity 6.
Previous responses didn’t help however I did find a solution.
In the Package Manager on the far left column there is a selection for “In Project” and underneath that is “Updates”.
By going through that and updating all the packages that had updates it solved my issue. I had also previously regenerated project files though I don’t know if that helped or not. Its under Preferences → External Tools → Regenerate project files.

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You might try the suggestion in this post … let us know if it works.

https://forum.unity.com/threads/eventsystems-does-not-exist-solved.675526/

I have also noticed that UnityEngine.EventSystems is not listed in the current API, but it is in the 2018.2 API.

5

Meet the same problem. Download several packages(visual studio editor, visual studio code editor, unity UI) in the Package Manager and the problem goes. It’s a really weird bug.