Locked out from Epic Games Launcher after adding Plugin to fresh install of UE 5.6

Development Getting Started & Setup
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21

The problem is not the engine. It’s the Epic Games Launcher that crashes. If you take a look into the log you should see some

[2025.06.12-20.17.13:880][518] LogCommunityPortalAppManager: RequestAppInstall: Add INSTALL action for artifact Hash:PluginName

[2025.06.12-20.17.13:880][518]LogCommunityPortalAppManager: RequestAppInstall: Inserted UNCHANGED action for main game artifact (null):(null):(null) at index 0
[2025.06.12-20.17.13:883][518]LogWindows: Error: appError called: Assertion failed: IsValid() [File:D:\build++Portal\Sync\Engine\Source\Runtime\Core\Public\Templates/SharedPointer.h] [Line: 890]

I think everybody is affected by this since today. Same reports in UE Discord channels as well.

22

Yep, This error is cause of that stupid fab marketplace or something. This is so annoying! wasted 5+ hours on this already :((

23

If you go to the install directory of the launcher, there is a Data folder and then a Download Manager folder. Delete the JSON file in that and the launcher should start up again.

4 Likes
24

C:\ProgramData\Epic\EpicGamesLauncher\Data\DownloadManager

json erased and it works! Thanks.

BUT. I cant update my plugin.

25

But this download manager folder does not exist for me :frowning:

26

C:\ProgramData is a hidden folder.

27

There’s really no other way to install a Fab plugin except through the Launcher?

29

Cool. Still can’t reinstall a crucial plugin. Guess I just won’t work on anything until Epic fixes their garbage launcher or lets me use a previous version.

30

Here’s my solution: go to the downloads tab and cancel the downloads you have in the queue. In my case, the Odyseey plugin had been left in the queue.

https://forums.unrealengine.com/t/about-epic-launcher-crash-fix/2553941

31

not an option when the project requires a plugin you now need to fresh install.

32

what is clear is that the problem is in the download queue, both my solution and the one put above to delete the json, in the end it is the same solution, if it does not let you enter the launcher you have to delete the json, if it lets you enter the launcher for a few minutes, you can cancel the queue from there, anything you are going to install will crash, be it fab plugin, quixel plugin, odyssey, or any other asset, it will crash, right now it is the only solution to be able to be inside the launcher without crash, but to install the plugins or assets without crash there is no solution, it must be something internal to epic games

edit: it only happens in engine plugins, not in other asset types

33

I can too confirm that this solution works for now, but as others stated you cannot install any plugin because as soon as the directory

C:\ProgramData\Epic\EpicGamesLauncher\Data\DownloadManager

populate itself with a Json file the program instantly crashes. I guess we’ll have to wait for Epic to patch it…

2 Likes
34

It’s not really a solution if you need the plugin. As soon you would install it you get crashes again. I bought one a day ago and can’t install it now.

35

The launcher just updated for me. Someone verify if this update fixes the issue?

36

For me, it worked.

Thanks Epic

37

Hey there @HonorDev! Welcome to the community! There was an update pushed to the launcher that was geared towards correcting this issue. Did this correct the issue for you?

38

Hey updated the Launcher now and am able to reinstall the engine. Seems to work. Will write again if the issue still persists after the installation.

39

Launcher update fixed the issue. I had some error that prevented me to install one plugin at first but after installing another one the first one even installed without issue. So everything looks fine now. Thanks.

40

The Epic Launcher update fixed the problem. Successfully migrated to 5.6 with installed plugins :slight_smile:

1 Like
41

Im experiencing a similar issue where i cannot install any engine versions, install button is available click it then the Fab spinner goes gray for about 30 seconds then nothing happens then sometimes when i exit the launcher i get an UE4 crash screen with the same error listed above. Tried all forms of removing all epic content including a Rivo uninstall, reg clean, app data clean etc nothing worked. Got so fed up i just tried on my laptop that has never had any epic software on it and the launcher exhibits the same issue cannot install any version of the engine so i think its still BRICKED!!!