Epic Games Launcher crashes moments after starting

I downloaded the new launcher update. Then, logged in at the login window as usual. Then the main launcher program shows up for a few seconds, but after a few moments it always crashes. This never happened before the update. I need immediate help on this, I can no longer access the content that I payed for.

Here is the error I am getting, which I assume is causing the crashes:

LogWindows: === Critical error: ===
Assertion failed: ItemType == EVaultItem::Type::Plugin [File:D:\BuildFarm\buildmachine_++depot+UE4-LauncherLive\Portal\Source\Layers\Presentation\Private\VaultItemViewModel.cpp] [Line: 418] 

That was from the debug log. The whole log is attached here.

Thanks to anyone who can help,


P.S. I honestly wish there was a way to control when the launcher updates (instead of it doing so automatically), along with the ability to downgrade it if necessary.

Hi ,

Sorry to see you’ve hit a problem here! This crash is caused by corrupt or missing data in your vault. The vault is located here:
D:\Program Files\UE4\Unreal Engine\Launcher\VaultCache

You should see a list of directories there, moving them all to somewhere else should unblock you immediately, but you’d have to re-download something you use again. You could find out exactly which one causes the problem by dropping them back in one by one or in small groups to see what causes the crash, to avoid needing to re-download all.


On further inspection of your log, it’s seems you have a UE_4.3 folder in there, which was cause by a bug that existed a while ago - my bet is that this is the one causing your crash!

Indeed it was the UE_4.3 folder! I moved it somewhere else and that immediately fixed the problem. Thanks for your help!

I have this EXACT same error and same entry in my log file as well. I do have my vault on a NAS drive though with a redirect on the folder. Its only been an issue since upgrading to windows 10. I am deleting all my 4.2 + 4.3 content from my vault now to see if this fixes my error too (I will report back if it does or does not work, here is hoping it does :slight_smile: )

UPDATE: Yes this appears to have fixed my issue too. Looks like the latest launcher has some issues with 4.2/4.3 content I deleted all of my old library data from those build versions and the launcher is now stable again. Thanks Swifty :slight_smile:

Great! Glad to hear you are fixed :slight_smile:

Just to clarify, it is only corrupt or incorrect data that causes the problem. It is fine to have normal 4.2 / 4.3 content.

There was a bug some time ago that made an engine install get dropped into the vault cache folder, and this is by far the most common cause.

I am also having this issue. My VaultCache is clear. The first time I log in I am able to see the front page, but when I select the Unreal Engine Tab it crashes. I have reinstalled and checked that all of the other tabs load properly.

Hi kaufdaddy,

I believe you are having a different issue. Please take a look at this post and try the solutions there. If nothing works, please create a new post in the Installation & Setup section and include the needed info.