Consistent "copying assembly from 'Temp/UnityEngine.TestRunner.dll'." error.

Every time I load a project I am greeted with the error: Copying assembly from 'Temp/UnityEngine.TestRunner.dll' to 'Library/ScriptAssemblies/UnityEngine.TestRunner.dll' failed. This happens on loading an existing project and when creating a new project.

It happens with all versions of Unity 2019. I am currently using 2019.2.6f1, but I have tried the latest version and had the same error.

I have searched around and seen people have similar problems, but none of the proposed fixes have worked.

When I reimport the scripts, I get a new error: Copying assembly from 'Temp/Assembly-CSharp.dll' to 'Library/ScriptAssemblies/Assembly-CSharp.dll' failed.

I have run multiple virus/malware scans and found nothing.

I have disabled all anti virus and still have the same issue.

I have noticed that the 'Library/ScriptAssemblies/' folder is empty. I assume that's part of the issue.

I was working on a project 12 hours ago and it was working without issue. I shut my computer down for the night and today I am having this issue across all projects. What do I do?

EDIT: Forgot to mention, I also tried loading Windows 10 into Safe Mode, and that did not help. Same error(s).

EDIT2: Further investigation, when trying to build the project in Visual Studio I get the error: "Could not copy the file "obj\Debug\Assembly-CSharp.dll" because it was not found."

 

Update: I've tried uninstalling and reinstalling Unity. No change.

 

Update 2: Apparently Unity v2017.4.38f1 works fine.

Edit: And v2018.4.19f1 also works.

 

I'm having the same problem it just started today for no reason.
I have tried everything I can think of but I can't even click play because of the error.
This has brought my work to a halt.

 

Also 9 times out out 10 if I close Unity and try to open it again it crashes midway.
I get this error in the log:

Faulting application name: Unity.exe, version: 2019.3.6.16304, time stamp: 0x5e719874
Faulting module name: mono-2.0-bdwgc.dll, version: 0.0.0.0, time stamp: 0x5df6ec43
Exception code: 0xc0000005
Fault offset: 0x0000000000315758
Faulting process id: 0x9ed0
Faulting application start time: 0x01d600a39e0ce8b7
Faulting application path: C:\Program Files\Unity\2019.3.6f1\Editor\Unity.exe
Faulting module path: C:\Program Files\Unity\2019.3.6f1\Editor\Data\MonoBleedingEdge\EmbedRuntime\mono-2.0-bdwgc.dll
Report Id: d53b5f65-45fb-4cf2-8d8b-8b1d544ed3ed
Faulting package full name:
Faulting package-relative application ID:

When it does boot into Unity I get the error " Copying assembly from 'Temp/UnityEngine.TestRunner.dll' to 'Library/ScriptAssemblies/UnityEngine.TestRunner.dll' failed." and although I can do things I can't click play because of the error so I have no way to test things.

 

I don't have the crashes but other than that we seem to be having the same issue, and it also just started today for me as well. This is beyond frustrating.

 

Update 3: the beta version for Unity v2020.1.0b2.3333 works fine as well. This seems to be a Unity 2019 issue, that just popped up today, without updating anything. This doesn't make sense.

 

I still get the error in Unity v2020.1.0b2.3333

 

I am also getting this error.

I tried:
- Deleting temp folder.
- Deleting library
- Reinstalling Unity and Unity Hub
- Deleting project folder and re-cloning the project
- Updating Windows
- Updating video drivers
- Scanning PC for malware
- Rolling back video drivers
- Rolling back windows installs
- Safe mode

 

After a lot of research I think my problem was a virus.
I did install a new app around the time the problem first started.
None of my antivirus tools were able to find it.
I reinstalled the OS and it is working fine again.

 

Oh god no... I have Avast and it has always blocked everything up to now...

 

Any one who has this problem, you have 2 Trojans on your computer that are downloading bitcoin you need to dl this program https://www.malwarebytes.com/mwb-download/ run it do the free trial version, set up and scan your computer it will find the 2 Trojans then press the quarantine button, then close unity and open it, the problem is gone, the program costs $30 for the full version but it gives you a 30 day trial, I am 100% going to buy this when the trial runs out. If any one is trying to do the fps microgame tutorials and can get the play button two start because of the two errors this is the fix its them lil bloody Trojans stopping you from getting ahead in unity. hope this helps.

cheers

john.

 

it disappeared for me when I enabled the new input system and disabled the old input APIs

 

How is this done? Sorry im a noob at this and it's just started happening to me

 

pls see:
https://docs.unity3d.com/Packages/com.unity.inputsystem@1.0/manual/Installation.html

 

That worked for me. Start around 4mins in the video

 

For me, having installed Anaconda, it wrote to Autorun in Computer\HKEY_CURRENT_USER\SOFTWARE\Microsoft\Command Processor (can get there through Registry Editor (search in windows 10)) -- and this was causing the issue for me. Simply clear the data value and hopefully that will fix this problem.