Unreal Engine 4 Launcher Crashing when pressing "Library" button

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

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

I remember seeing launcher telling me yesterday, a few moments before it crashed, that 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 engine installed then (also when bug started to occur), but after uninstall I can’t even get it back as I can’t access page.

This is inconvenient to say least. It would be great to know how to fix this as I’m going to use 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 troubleshooting steps in link below. Afterwards, if issue persist please follow steps at bottom and page and post your ‘Verbose Logs’. They will help us track down issue.


I’ve been trying to get Verbose Logs after crash. However, when I go to folder that is supposed to have “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 engine folder. Also, maybe unrelated, sometime when I open 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 logs, I got it right there. engine still crash though.

Hi Lurianar,

i think your crash is caused by corrupt content. Could you try rename 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 crash still occur… I then deleted folder and appdata folders of UnrealEngine and UnrealEngineLauncher, but launcher still crash when pressing “Library”.

Would it to be possible to get newer log files since you tried delete? In theory, if problem is caused by a corrupt cached image, you should see, after deleting folder, launcher runs fine 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 cache. I’m wondering whether perhaps after removing content cache directory, you are experiencing a different crash.<\br><\br>It would also be awesome if it was possible to 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 inconvinience,<\br>Leigh

Content Cache


Now, one thing that I find curious is that contentcache folder contain only one picture, which is one appearing on main screen on launcher. I also joined 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 content cache. Most likely somehow a 0 byte png file. I’m afraid 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 launcher under “My Projects”, to see if they have a broken png file next to it’s uproject file, or file at [Project]/Saved/AutoScreenshot.png<\br><\br>If my suspicion is right, then project browser of editor for which particular project gets listed in will also crash in same way when trying to list projects.<\br><\br>Hope that helps!<\br>Leigh

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

What I don’t understand though is how it could get corrupted in 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 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 content cache. 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 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. former in particular is good to reduce your risk of losing work in any circumstance.

Thanks! And 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 launcher again and fix will be in an upcoming release :slight_smile: