I have all my game project’s content for 4.26. But since 4.27 is here, should I migrate the project to 4.27?
It won’t be easy, there may be some risks. I will consider updating the project only if it is really worth it.
The most important part is, which version is more stable, and which one is buggier?
Possibly?
The rendering side of things is still a heck of a lot slower than .25
But .27 seems to be better than .26.
Not by much.
Re your last question.
They are all pure 
.
You need to go back to something like .18, then maybe the engine was working OK-ish.
And, don’t “convert in place”. Just make a copy and convert that.
You can’t revert to older versions so keep the old versions instead.
My main issue with 4.26 is after using it for like 10 minutes or so, the right click menus start to not open. Sometimes these menus flicker instead of opening.
And since 4.25 sometimes the screen goes black for a couple seconds. Especially when opening a new blueprint.
If those bugs are addressed in 4.27, that would be my reason to migrate.
This is mainly nVidia’s fault though:
That figures. Thanks for the link!
And since 4.25 sometimes the screen goes black for a couple seconds.
I updated my GPU’s Displayport Firmware and those black screens went away > NVIDIA Graphics Firmware Update Tool for DisplayPort 1.3 and 1.4 Displays
Is not 4.27 the last in the 4.x tree? I thought the path-forward was to migrate to UE5 past .27?
I installed that reg file and suddenly Netflix started to go black screen once in a couple seconds. I didn’t even try Unreal editor.
It says the file disables multiplane overlays. What may that be?
That update didn’t run in my system. Found it incompatible. I think mine is more up to date.
I can’t get any motion blur in cinematic render AT ALL.
I converted 6 levels from 4.26 (stupidly) and now have to re-design them ALL and go back to 4.26.
DO NOT convert in place!!
Re read that 100 times or so 
I’m having a black screen when opening existing or new projects in 4.27. There’s also a copy of the engine’s viewport tab in the lower left corner of the interface that I can’t remove or click on to do something. I can close application by clicking in the upper right where that X for windows is, but the display of the application doesn’t return to normal after a few seconds or so.
It happened after I updated to the NVidia Studio driver 472.47, so I’m attempting a rollback to 472.12. I’ve heard it has also helped some to change color to 8-bit and Full in the NVidia Control Panel, and/or change mode from RGB to YCbCr. But that was more related to HDR it seemed.
.27 is apparently just a problem.
The UI is twitchy when it runs. The modal or drop down menus keep jumping up and down and are unclickable off the launcher build.
Opening a .25 project from the launcher didn’t even ask about conversion. Let alone if a copy should be made.
That said @presto423 Nvidia studio drivers have always been problematic with the engine.
Not really sure how or why, since studio drivers are supposedly meant to provide better access to programs like the engine, but back in .25 one particular version of the studio drivers managed to BSOD the system when opening unreal.
I’m 100% blaming epic for it, but swapping to the game ready driver did solve the issue, so perhaps it was Nvidia’s fault after all.
Anyway, I have been tentatively swapping between game ready and studio ala-carte, when problems present themselves.
This time around, swapping or updating (there’s been at least 3 driver updates since .27.2) does nothing for the Ui.
Building from source did, but you know how that goes. Painful to say the least. Got to do it anyway to check out Chaos. But still painful.
Use general rule of thumb stuff.
Do a clean driver install.
Do a verify engine files.
Make sure the anti-virus or whatever else isn’t blocking or deleting parts.
And try a reboot when stuff doesn’t load (the oldest IT trick)
4.26 has been pretty stable and problem-free for me. Aside from when I first moved over, I had some issues with Dual Monitors, but that seemed to only happy with my first project. I’m hesitant to download 4.27. Unless you need the groom improvements, or you’re a virtual production studio, I don’t think 4.27 is necessary. Oh, or you’re planning to use pre-rendered video for cut-scenes. Then the Bink integration would be good.
I cant get UE4.27 to pack project. Niagara and many other in-engine plugins require Python plugin to be enabled. Switch wasn’t the case in UE4.26 and earlier. Python plugin then conflict with certain marketplace plugins and getting struct pointer errors from BPs. While play in editor and “Standalone Game” in editor both work without issues. Staying in UE.26, but bit worried if UE5 will have similar struct pointer errors or is it just some plugin conflict.
In 2025, would you still say that 4.25.4 is the best version of the engine performance-wise for a Direct X 11 project? I’ve used everything from 4.13 to 4.27.2 up to 5.4.2 over the course of several years, but have never done a direct side-by-side comparison using the same project. I did see one comparison that showed 4.27.2 to be around 40 fps more performant in a blank project than UE5, and from my memory, it did seem that I was able to hit higher fps in UE4.
.25.4 should be just right before the performance slump they have been on for 5/6 years started.
That, or it’s already within the slump, in which case 4.24 was right before?
I honestly can’t remeber.
I know .24 had loads of bugs introduced into it by sloppy coding that got quickly addressed in the git.
And i distonctly recall .22 breaking terreain/landscape physical materials.
Dx 12 also works for those versions btw. The only issue you really have on it is getting accurate FPs outputs when testing final builds. And the fps unreal itself gives seems fake to be totally honest.
Anyway, same exact scene in .27 performs around 40% worse than the competition which also ends up looking better; try Cry Engine if you can.
@MostHost_LA Thanks for that, I appreciate you taking the time to share your insights!