fatal error: another unity instance

hello, im getting this fatal error when i start up unity:

'it looks like another unity instance is running with this project open. Multiple Unity instances cant open the same project.'

i havent tried to open unity twice or anything like that, ive also restarted my pc and tried to delete temp folder for that game- however i cant as it says the folder is corrupted and unreadable. Any ideas?

 

It means your project is permanently corrupted and there is no way of restoring it, You will have to get all of your assets and put them into a new project. I thought they fixed this in 4.2 but it looks like they didn't which is really sad despite the fact I've opened multiple bug reports and had many, many replies with people reporting the same issue. The only "fix" they seemed to have done is by removing the project corruption error you used to get and replacing it with this one.

This is why you should always do backups

 

Boy am I glad I didn't listen to you.

Just duplicate the folder as a copy and rename it to whatever you want. It'll open fine.

 

Actually just delete the UnityLockFile in Temp. That's what worked for me.

 

Thanks Benjins! Temp/UnityLockFile was the issue.

 

Thanks Benjins! that was the problem

 

check your projects permission

 

I had the same problem when I had to kill the Unity task because it would not finish.
I could not find Temp/UnityLockFile... maybe because I am running 4.7.1.
But I saw that ProjectSettings\ProjectSettings.asset was changed so I reverted it to a previous version and that fixed it. Whew!

 

I had this problem when I updated my unity and try to open a project of an older version .
I try to delete Temp/UnityLockFile file, but it does not delete .
I turn off my PC and turn it on and my problem solved .

 

Thanks Benjins it's work！

 

Thanks Benjins. Worked for me.

 

I've tried deleting UnityLockFile, but that hasn't helped, it just gets recreated every time i try to open the project. I've also tried duplicating the project folder with a different name, but that fails in the same way. Elsewhere it was mentioned to try deleting all scripts, as they might be failing to compile, but this also did not help.

Any more ideas? This really is a pretty atrocious bug, it's making UE4 look more and more attractive.

EDIT: I uninstalled unity completely (5.5.4) and installed the latest version (2017.1), then tried to open my project (after making sure UnityLockFile was delete), it warned me about the version difference and mentioned that it might need to re-import everything, I clicked OK, then... nothing. The unity process is running according to task manager but nothing came up on the screen, not even the little loading box that sometimes shows.

EDIT2: After digging around for a bit i've found what might be a solution. First of all i checked the editor log file, which was reporting 'Native extension for WindowsStandalone target not found' right before the crash. Somewhere online it was mentioned that this might be related to a lack of internet access. I cracked open windows firewall, and looked at the list of programs that are allowed through the firewall, and saw that unity was listed twice for some reason. One version had only private network access, and the other only public network access. I changed both to have access on both types of network. Then I deleted the lock file, Ran unity 2017.1.1f again, and after re-importing everything due to the version change it managed to load my project. There are a few more warnings than before but everything appears to be in place.

Why on earth unity does not display some kind of error message or indeed anything at all after this kind of crash is just beyond me.

 

Here is quick solution

Just Open Unity as Normal
Create a new project name it whatever
From the new project GoTo File / Open Project
Open the Project that was showing the error
It should be able to open up.

K BYe

 

I have the same problem. None of the answers on this string solve the problem. Any other ideas recently?

 

Had to delete whole /Temp folder - it stores files from the previous Unity attempt to open the project. It worked for me.

 

hahaha LOSER, only erase the Temp/UnityLockfile

 

HOW I FIXED THIS:
1. Create a new project.
2. Close Unity Editor.
3. Delete the Assets folder of the new Unity project.
4. Paste the Assets folder of the new Unity project with the Assets folder in your old project.

 

It works for me too!

 

The way i fixed was
1.Created new project
2. then i went inside and delete the default scene folders
3.Then i imported only the assets folders that had the problem.

 

I have Unity 2019.2 a04 installed and after installing it, the error started popping up... the thing is, that even if i create a new project and open the new one, it does the same thing...
It does start though just gives the error and the unity hub pops up again

 

Just delete temp folder

 

hey Benjins no luck

same here brother.

 

You just need to click one time on the project to open project , If you click double times on the project to open than error message appears. So click on project only one time on unity hub .
please reply if works .

 

yep it works
thanks dude im just a biginner for unity lol

 

I can confirm that deleting only the UnityLockFile doesn't fully help. But deleting the full folder Temp does.