Unreal Engine 4 Launcher Crashing when pressing "Library" button

I can’t even download the engine itself. Basically, whenever I press the Library button, I get the following message (along with an appcrash): The Following Process has crashed: Unreal Engine Launcher

You do not have any debugging symbols required to display the callstack for this crash. I tried uninstalling/reinstalling, clearing up the cache folder, changed the hard drive it installed… I also have all the necessary component tu run UE4 as yesterday it was running just fine.

I remember seeing the launcher telling me yesterday, a few moments before it crashed, that the engine required 10gb of free space and warning me that I didn’t have enough (even though I had 30+gb on my SSD hard drive). I had the engine installed then (also when the bug started to occur), but after the uninstall I can’t even get it back as I can’t access the page.

This is inconvenient to say the least. It would be great to know how to fix this as I’m going to use the engine very soon. Thanks!

Hey Lurianar,

We are sorry to hear that you are experiencing this issue. We have assigned this to a member of our support staff for investigation, and they will follow-up with information or questions concerning this issue as soon as possible. Thank you for your patience.

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Thank you!

Hi Lurianar,

Try the troubleshooting steps in the link below. Afterwards, if the issue persist please follow the steps at the bottom and page and post your ‘Verbose Logs’. They will help us track down the issue.


I’ve been trying to get the Verbose Logs after the crash. However, when I go to the folder that is supposed to have the “saved” folder, all I get is one called “spool” and two files named settings.yml and users.dat. I do not have any log files and yes, I did update my DefaultEngine.ini in the engine folder. Also, maybe unrelated, sometime when I open the launcher, I get “Not Installed, Unreal Engine 4.4.3” and sometime I get “Not Installed, Unreal Engine 4.4.0”.

Any idea of what could cause this?

link text

… nevermind for the logs, I got it right there. The engine still crash though.

Hi Lurianar,

i think your crash is caused by corrupt content. Could you try rename the following folder and see if that helps<\br>
C:\ProgramData\Epic\UnrealEngineLauncher\Data\ContentCache <\br>
to <\br>
C:\ProgramData\Epic\UnrealEngineLauncher\Data\ContentCache_old <\br>
or something

In this case it turned out that a project had a png file for it’s thumbnail or screenshot that was 0 byte. So that is another avenue for workaround.

I tried renaming, but the crash still occur… I then deleted the folder and the appdata folders of UnrealEngine and UnrealEngineLauncher, but the launcher still crash when pressing “Library”.

Would it to be possible to get newer log files since you tried the delete? In theory, if the problem is caused by a corrupt cached image, you should see, after deleting the folder, the launcher runs fine the first time (as it used images from http not cache), and therefore we should see a log file that shows all images downloading rather than coming from the cache. I’m wondering whether perhaps after removing the content cache directory, you are experiencing a different crash.<\br><\br>It would also be awesome if it was possible to zip up you content cache folder and put that here for me to test against, but it may be too big.<\br><\br>Thanks! And sorry for the inconvinience,<\br>Leigh

Content Cache


Now, one thing that I find curious is that the contentcache folder contain only one picture, which is the one appearing on the main screen on the launcher. I also joined the logs. Hopefully this’ll help in figuring what’s going on :slight_smile:


Ok, i think I may have figured out that this is actually caused by a broken png file in one of you projects rather than the content cache. Most likely somehow a 0 byte png file. I’m afraid the only way i can think that you will find it is if you go check all of your projects that you have that normally show in the launcher under “My Projects”, to see if they have a broken png file next to it’s uproject file, or the file at [Project]/Saved/AutoScreenshot.png<\br><\br>If my suspicion is right, then the project browser of the editor for which the particular project gets listed in will also crash in the same way when trying to list the projects.<\br><\br>Hope that helps!<\br>Leigh

Ok I’m able to download with the launcher once again. This makes a lot of sense as the problem started when I was inside the engine, and would correlate with the fact that the launcher kept telling me I didn’t have enough free disk space (thus the corrupted 0k file). I’ll update as soon as I launch the engine to let you know if the problem is fixed in-engine.

What I don’t understand though is how it could get corrupted in the first place? I only started blueprint projects and didn’t make anything custom yet. Is it a known bug or should I actually pay attention not to do something in particular? I’d hate to have a project corrupted the same way (even with backup, sometime it’s easy to lose 4+ hours of work).

Yea, it’s a good question! How do these files get corrupt or written empty? I know I’ve seen that a few users have experienced some form of corruption with the content cache. The usual suspects are programs crashing while writing files (akin to power cuts also), faulty hard drive, third party virus/security software, and of course, bugs etc, but that’s still pretty vague.

I think you might be on to something with the hard drive space issue so I’m going to investigate that a little and will comment if i find anything.

For now though, I guess I can just recommend good use of version control software, and working on drives with enough spare space on them. The former in particular is good to reduce your risk of losing work in any circumstance.

Thanks! And the engine works now :slight_smile: It’s good to know I’ll finally be able to start working on my project. I hope my problem will be able to help in any way to improve and/or help!

Great! Yea this helped, I can now make sure that this situation cannot crash the launcher again and the fix will be in an upcoming release :slight_smile: