Help needed after upgrading to 5.5.. CS1704 UnityEngine.UI already imported error

Hi everyone,

I need some help with this.. sorry if it is a duplicate to something already asked.. If so, please point me to the solution or thread.

I just upgraded Unity to 5.5 from 5.3.6f1 and can't quite figure out how to resolve an error. If anyone would be able to offer me some help here I would really appreciate it. I pasted the console output below.

Thanks,
-Kory

error CS1704: An assembly with the same name `UnityEngine.UI' has already been imported. Consider removing one of the references or sign the assembly
C:/Art_all_programs/Unity/Editor/Data/UnityExtensions/Unity/GUISystem/UnityEngine.UI.dll (Location of the symbol related to previous error)
C:/Art_all_programs/Unity/Editor/Data/UnityExtensions/Unity/GUISystem/Standalone/UnityEngine.UI.dll (Location of the symbol related to previous error)
error CS1704: An assembly with the same name `UnityEngine.Networking' has already been imported. Consider removing one of the references or sign the assembly
C:/Art_all_programs/Unity/Editor/Data/UnityExtensions/Unity/Networking/UnityEngine.Networking.dll (Location of the symbol related to previous error)
C:/Art_all_programs/Unity/Editor/Data/UnityExtensions/Unity/Networking/Standalone/UnityEngine.Networking.dll (Location of the symbol related to previous error)
error CS1704: An assembly with the same name `UnityEngine.HoloLens' has already been imported. Consider removing one of the references or sign the assembly
C:/Art_all_programs/Unity/Editor/Data/UnityExtensions/Unity/UnityHoloLens/Runtime/UnityEngine.HoloLens.dll (Location of the symbol related to previous error)
C:/Art_all_programs/Unity/Editor/Data/UnityExtensions/Unity/UnityHoloLens/RuntimeEditor/UnityEngine.HoloLens.dll (Location of the symbol related to previous error)

Compilation failed: 3 error(s), 0 warnings

 

well I fixed it... Closed the editor and restarted it...

 

it worked after i restarted my editor
tnk u

 

Simply restarting the editor did not fix this issue for me.

Rebuilding the Project Library by deleting the 'Library' folder and reloading the project this way however did solve it.

 

Finally upgraded to 5.5 from 5.3.x and playmaker is throwing this error. Do I delete the whole Library folder or just the metadata? Thanks in advance.

 

The entire folder. Let Unity rebuild everything from scratch so you won't have any other issues.

 

Yes this worked I was almost at my wits end and thought I'd have to start all over again! Thanks so much!

 

Thank you @Ghosthowl, I was throwing 23 editor errors after updating without any luck on restarting my cpu or unity.

Deleting the library folder and having unity rebuild it from scratch did the trick. Cheers.

 

This did the trick for me. Thanks!

 

I'm getting a similar error for

Code (CSharp):

1. error CS1704: An assembly with the same name `XInputDotNetPure' has already been imported. Consider removing one of the references or sign the assembly
2. Assets/Plugins/x86/XInputDotNetPure.dll (Location of the symbol related to previous error)
3. Assets/Plugins/x86_64/XInputDotNetPure.dll (Location of the symbol related to previous error)
4.  
5. Compilation failed: 1 error(s), 0 warnings

But deleting my Library folder (cache) does not solve it.

 

The import settings in XInputDotNetPure are wrong.
Assets/Plugins/x86/XInputDotNetPure.dll should be x86 only.
Assets/Plugins/x86_64/XInputDotNetPure.dll should be x86-64 only.
Unity no longer uses the hardwired paths that it used to to determine the platform, as of 5.0.

 

Yup. That's exactly what they are set to:





It's the first thing I checked. The settings were correct and it's still happening.

 

Those are the platform settings for standalone builds, check the editor platform setting as well, it's the Unity icon tab.

 

My problem is actually with Standalone builds.

Regardless, the architecture is also set correctly for the Unity Editor.

 

Unfortunately I'm out of ideas! :-/

 

Thank you for your help though!

I deleted the plugin to 'solve' the problem.

 

Restarting the editor also fixed this issue, along with several other compilation issues.

 

Hi, may i know where is the library files?

 

It's just the Library folder

 

thank u MrKory it solved the probleme for me too

 

WORKED! JUST RESTART THE EDITOR thank you everyone

 

Just close the editor and restart my unity setup its work great and resolve this issue........

 

this is still broken here
error CS1704: An assembly with the same name `UnityEngine.UI' has already been imported. Consider removing one of the references or sign the assembly

 

Hi everyone.
Here is what worked for me for the error CS1704.

In my case it was unity.tasks.dll and system.data.dll but I suspect the solution will work for most people with the error CS1704.

I looked at this " Consider removing one of the references or sign the assembly Assets/PlayServicesResolver/Editor/Google.VersionHandler.dll (Location of the symbol related to previous error) " part of the error and noticed that the file names were the same. I looked at both versions of the dll files properties and then renamed the oldest version to <name>.dll.old and then recompiled to see if it would work. Eureka.

I am a noob, so not sure why this is but here is my theory:
Unity keeps a record of the plugin libraries for name space resolution (I think) which it rebuilds when something changes. (See Assembly-CSharp.csproj under project root, just a guess)
When a new plugin gets added (or in my case I moved to dotnet 4.x from 3 ) it may contain the same dll of the same or different version. The name resolution records then ends up with 2 entries with the same name, for two different files. This means that a call to that library cannot be properly resolved.

I hope that someone smarter than me reads this and corrects or improves my explanation so that I can learn to understand this better.

Anyway, hope this helps someone.