I encountered a similar problem when working in a prefab. it kept showing an asset progress importing popup for just a sec every time i did anything. It turned out it was the autosave on that prefab. Even though the popup shows a different prefab. i just turned auto save off and it seemed to fix it. Hope someone finds this useful
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I just upgraded to the release version of 2019.3.0f6 and when opening my project I’m getting this, importing (iteration 3) at the moment.
The project is big. will this iterate more times? is it intended behaviour? or should I end the process and open the project again.
Edit. I did just that and now it only imported once.
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hey, did anyone figure out how to solve this problem? I just downloaded Unity 2019.3.0f6 and I’m having this same Asset Import iteration problem!
@JeffDUnity3D I think I found the cause of this problem - at least why it’s happening in the project I’m currently working on. We are using Addressables and we call PlayerPrefs.DeleteAll() when the user starts a New Game. This tedious importing start basically every time I go to play mode and it’s doing importing for minutes!
But I found out that Addressables 1.6.0 saves info into the PlayerPrefs:
BuildScriptFastMode.cs
BuildScriptPackedPlayMode.cs
BuildScriptVirtualMode.cs
AddressablesImpl.cs
I found that in the Build… files the Addressables.kAddressablesRuntimeDataPath is set to a value and the AddressableImpl uses this value. If I just start the game without starting a New Game no importing happens on next start so it’s very suspicious. And if I start a new game there is importing on the next start.
I found another file in the com.unity.render-pipelines.universal@7.1.6:
MaterialPostprocessor.cs
This one gets a key which is the ‘curUpgradeVersion’ and if that doesn’t equal to ‘lwrpVersion’ it does AssetDatabase.ImportAsset() calls.
You can find the problematic parts in the files by searching for PlayerPrefs.
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I Found the problem / Problems that are causing this
Normally SteamVR and OculusVR integrations has an option that autoenables it for you
so when you are trying to uninstall your Standalone VR plugins
you have to uncheck “Virtual Reality Supported” in player settings first
But then you realize that it enables automatically so you can not disable it
this is the main problem when you are triying to uninstall VR Standalone plugins
there are a few steps you must follow firts before deleting them
and i will show you what to do;
Disabling oculus “Use required project settings”
I have it unchecked already (but you will see a tick)
Disabling SteamVR “Auto Enable VR” in SteamVR_Settings ScriptableObject
You can find it by searching SteamVR_Settings in project window
And then you should be able to Disable “Virtual Reality Supported”
And it will not auto reenable again!
Then you will be able to uninstall the standalone VR packages correctly
And then Install the New plugins from XR Management window
YAY! FIXED!
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I had recently downloaded the PlayMaker equivalent of this and forgot to de-link them after testing. Thank you very much for this post! 
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I’m going to try this after I back up my project…
I am having this same problem. But I don’t use VR at all. And I’m not using PlayerPrefs.DeleteAll() function anywhere in my project either.
I am upgrading my project from a previous version to Unity 2019.3.3f1. My project is very large in size, and I’ve been letting my computer import for about 12 hours now, and it’s still going through iterations. One screen said 1 out of 3723 and I think it goes through 10 iterations for each of these 3723 items… that’s A LOT of importing and could probably take all year, literally 
Anyways, if anyone knows why it’s doing this or a fix for it, it would be great.
Going on 13 hours and it’s still importing lol.
Thats another bug that was fixed in unity 2019.3.5f1
Updating to the last version should fix that
That would be great. I hope so. Thank you.
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Iteration(version 2) importing window constanly showing up in my old project. Unity version2019.3.13
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For me the same, after installing new Unity Hub 2.3.2 and Unity 2019.3.14 on Windows 10 Home
After a few reinstallations of the Unity engine, I realized that it would not help and I’ve solved in the following way:
- completely removed all the Unity versions and UnityHub;
- manually removed all the files on my PC which are somehow connected to the Unity or UnityHub;
- with the help of utility like CCleaner cleaned up garbage and registry;
- reboot the computer and install everything again;
It works now.
I just switched back to asset version 1.
And there is no Disturbing windows pop up at the center of the screen.
But it is deprecated.
If this thing will not be fixed I do not know how one can work on any intermediate project in asset version 2…
Ran into this endless iteration loop. an entire day pissed away and continues! Why is this issue still present in 2019.4?
I’ve found another reason for this. I’m using NordVPN and when this app is active (so I’m connected to the VPN server) Unity doesn’t start (endless splash screen).
That is different issue.
I had this issue as well. In my case, simply disabling auto-save for the prefab fixed it.
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I had a custom editor script which in the OnEnable was calculating some values to save, and setting the prefab dirty. This was fine on 2018.4 but on 2019.4.2 would cause an infinite loop of trying to load/import the prefab. My workaround for now is just to comment out where it set the prefab dirty in the editor’s OnEnable until I find a different way to implement it.
So Why is there no response from unity on this issue… Upgrading project to The newest LTS causes this never ending loop of importing iterations… Every time unity compiles this happens… What Do we do?? Any ideas?? WE can always go back to the version before trying the 2019.4 LTS but man why is this always a mess… Thanks in advance for any help
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