UE 4.9.x stalls on import (OSx)

When you attempt to import anything into the Content browser the system will lock up. You cannot access any other software nor can you attempt to Force Quit it. All you are able to do, if you want to import something is wait it out, this could take up to 4 minutes. I have experienced this issue across multiple computers, ranging from a Macbook Pro 15" to a MacPro (tower not trashcan).

Thank you

Hi ga1lyons,

You have stated that you experience this issue on a variety of Macs ranging from the MacBook Pro 15" to a MacPro Tower; In order to isolate this more efficiently, do you have access to just the MacBook Pro 15 -so we can compare “apples to apples?”

Starting off, please supply your Mac’s specs located here: Apple menu >About This Mac>More Info> Add the information from this window (serial # not necessary).

Also how are you importing assets into the Content Browser. (ie. dragging and dropping, or navigating from the Content Browser starting by pressing the ‘Import’ button in the editor?)

Please provide this information and we will continue to investigate from there.


MacBook Pro (Retina, 15-inch, Mid 2014
2.8 GHz Intel Core i7
16 GB 1600 MHz DDR3
NVIDIA GeForce GT 750M 2048 MB
Mac pro (2012 mode (june 2012 model MacPro 5,1)
16gig ram
3.2ghz quadcore
Nvidia GTX 650 1gb

I have attempted to import through the import button, and navigating to location (folder located in top level of project directory) also through RMB and using import on that menu. To be honest i had not tried to Drag and drop into the content browser, just did; images and .fbx’s both work without delay.

My first thought was that there was an issue with my scene or other, but this repeats on new projects.

Does this only occur on the first import - ie subsequent imports are fast?

If so, this may be related to just displaying the finder window.
I get this in UE when packaging - only the first time when it tries to display a file dialog box. Interestingly, it does not occur for me on import, only when selecting folder for packaging.
It does occur in a few other apps for me, in select circumstances.

I believe the issue may be related to Finder and Cloudkit.

If this is indeed your issue…then here is a possible fix ( which I have not tried yet)

I followed the possible fix and it did not address the issue.
This occurs in no other apps for me and occurs on first then intermittent imports afterwards however the later stalls are not always as long as the first.

Hi ga1lyons,

If I understand you correctly: There is lag when you import assets by using the import button and directing to the file(s). There is NOT lag when you simply drag and drop assets into the content browser?
Let me know if that is correct.

…Also, please try running the Activity Monitor while this happening to check the CPU and RAM usage among other things. Here’s a link that expands on troubleshooting with the Activity Monitor:
Troubleshooting with Activity Monitor

Did as you suggested regarding activity log, I also attached a screenshot.
When you drag/drop in there is no more of a lag as opening a file (or any normal import) When you use the import commands it stops whole machine.


Hi ga1lyons,

I’m sorry I wasn’t clear before. In order to properly evaluate the issue, we need you to sample the editor in Activity Monitor by opening the Activity Monitory, selecting the editor in the list, then use View->Sample Process to generate a report on app’s current activity, then save it as a text file.

Please do this and post a copy of the text file here.


Hi ga1lyons,

Since we have not heard back from you in a while, I am marking this post resolved for tracking purposes. However, if you are still experiencing an issue with your Mac lagging when importing assets through the Import option in the Content Browser, simply respond to this thread and we will continue to investigate. As I mentioned previously, we will need an Activity Monitor sampling taken while the stalling is occurring. *See previous post for instructions.

Thanks for your cooperation in resolving this issue.