Thanks to some recent issues to what I can only presume to derive from the launcher update this past week, Unreal Engine 4 launcher versions now no longer function properly with the majority of Unreal Engine 4 projects. I have been able to reproduce this on nearly every computer I own in my office. So far, I have tried both version 4.26.2 and 4.27.2 and the majority of my projects running those versions are instantly met with the critical “Failed To Launch Editor” message.
This is because Epic has completely screwed up the editor executable pathing with their recent launcher updates, and now in order to open those projects, you have to manually open them with the UEEditor.exe from your binaries of the engine version it’s supposed to be opening with every single time. You can also set the default app to that editor.exe, but keep in mind you won’t be able to use both UE4 and UE5 simultaneously using shortcuts of any kind.
What is odd, is that some projects that I have C++ in running 4.26.2 have in fact managed to launch fine with no issues from their original shortcuts, without changing any executable to open them with. I have not done my research on this, but I would have to take a bold guess in saying source versions of the engines probably work with no issues right now.
I have no idea what the true cause of this is, and my claims of what are only irritated assumptions - but this is not cool for us Unreal Engine users who still like to use both UE5 and UE4. I hope this is fixed soon by Epic, and that they also pay more attention to what they are doing to the launcher because this whole past week it’s been a sh*t show with it if I am being honest.
If anyone else has further information or news on this I’d love to hear it. But for now, it’s an issue with an annoying workaround that needs to be fixed.
i thought i was the only one who was having this problem but no, seems like everyone is as well. but luckily i managed to find a solution to fix this problem. is that you download an old version of epic games app, install it and then it will fix the problems of launching the project files of unreal engine 4. you guys should try it out.
Glad I’m not the only one since just a day ago my project on 4.26.2 is now doing the same thing I really hope Epic fixes this issue soon because its a little annoying to have to open UE 4.26.2 first then the project every single time.
The problem is, before finding this thread I uninstalled UE4 and was in the midst of re-installing it, the problem is I can’t even do that, it’s giving me an error.
So I guess we just wait? For how long? Can we report this issue to Epic to expedite a solution?
The “new update” sucks, it kill all my 4.27 projects:
Cant open by normal way, have to go to launcher, find your project then open
Mess up the DDC config turn to default, welcome to red C driver
Cant package with “ERROR: System.ArgumentException: An item with the same key has already been added.”…this problem used to be fixed by delete duplicate plugins, but now it cant, event if i try to uninstall all UE4 plugins!
If Epicgames want to kill UE4, it will be a big problem with them!
I believe we all need to issue formal bug reports to Epic in addition to this thread and other threads like this one, and let them know it’s a major issue that does need to be addressed.
Temp solution: right-click on project’s icon → “Open with…“ → “C:\Program Files\Epic Games\UE_4.27\Engine\Binaries\Win64\UE4Editor.exe” (or where your UE4 is installed in) and check a box to always open with this program.
The above is not a solution as it will associate all uproject files with that engine version and mistakenly update projects which can be really hard to “undo” essentially migrating them in place for anyone using multiple verisons of the engine…. You’ve been warned! If you accidentally double click a 4.25 or 4.26 uproject it will open in 4.27.2 in this case.
The launcher has a pointer to “unreal engine” that directs the launcher "unreal engine” entry dynamically to its correct version where windows file associations will not understand this and will point all uproject to whatever Editor.exe you right click and override to.
You can use cmd and open as mentioned below in the video or launch the editor from launcher and pick the project to open manually as mentioned above.
The video below will go over how to correctly open a project with the correct engine version.
I found a simple solution for now….In the Unreal Launch, under your version (4.26.2 for me), click “Launch” like you’re going to make a new project. Then, when it loads, it will have the option to “Select or Create New Project” and you just click on your current project and double click it or select it and click open….it should load….Hope it helps until it’s fixed appropriately.
(aside: Reinstalling the Unreal Launcher itself didn’t help but you can try it anyways)
Currently to work around this issue for source bulids you can run the following command E:\GitUnrealEngine\Engine\Build\BatchFiles\GenerateProjectFiles.bat “D:\MyProject\MyProject.uproject”
