Hot Reload has been virtually useless since 4.17 - still not scheduled for a fix?

This bug makes Hot Reload pretty much useless. Any chance we can bump the priority on this? There also seems to be an issue where Hot Reload causes any USTRUCT UPROPERTY’s to be initialized to random values on hot reload.

This is a pretty core engine feature, bit of a shame to see it neglected.

I don’t have any news regarding the issue, although I’ve shared your feedback with our engineers.

Regarding “an issue where Hot Reload causes any USTRUCT UPROPERTY’s to be initialized to random values on hot reload”, this one doesn’t seem to be known to us. Can you please file a bug report?


Hi Stephen, thanks - I will file a report for that.

EDIT: It seems to be related to this issue: Unreal Engine Issues and Bug Tracker (UE-64076)

I’ve got some news on this one now. Our engineer took a look at it to see how easy it might be to fix, and found that the issue didn’t reproduce anymore in the 4.21 code. Our QA has now also tested and confirmed the same. The JIRA will be updated to reflect that shortly, but the good news is that 4.21 is coming up soon, and it seems like this one won’t be an issue anymore.


@TheJamsh Could you check if this was solved for you in the latest preview?

Not solved as far as I know, but I haven’t moved to a preview build yet. On Issues it’s marked as “Cannot Reproduce”, so if we get a fix now I imagine it’ll be by fluke.

There is also this one: Unreal Engine Issues and Bug Tracker (UE-52220)
The bug you experience is commonly known. I wonder why there isn’t more effort by Epic to fix it.

I can’t believe it has been a whole year and this is still a broken mess. I guess back to Unity and CryEngine again. Hope one day Epic will decide to take this as a priority since you know it’s a pretty major annoyance.

Epic already integrated and granted us a free license for Live++. Patch running app, even when playing in the editor? Beautiful!
I would never look back for the “Hot Reload” thing.

I just waiting until Live++ magicians would figure out how to patch the program after changes in the class layout.

They would both run into the same bug I would imagine.

lol if you think Unity is any better you haven’t used Unity 2019 for long…

I think ultimately what causes these bugs hard to track is Unreal’s ever increasing modularity.
But modularity is not a bad thing, unless you’re working with Unity :stuck_out_tongue:

Someone has a PR to fix the bug since like last year though. Epic just doesn’t think it’s important enough to be merged. That or people just accept hot reload is broken and moves on using Blueprint entirely or closing editor when using C++.

Yes I really doubt that Fortnite teams use HotReload, coders make “new nodes”, designers use new nodes…
Coders don’t even need to use the Editor.

What’s the issue here exactly? When I’m writing a new thing or refactoring features, I keep working in Visual with editor opened and then restart it one or two times a day.
Grab Unreal VS extension so you can easily specify a map to open on the editor’s start. After that, you just need to hit this “restart process” button in VS and your editor is back after a minute.
Honestly, recompiling bigger parts of project in Unity isn’t significantly faster. (Perhaps is better now since they’re finally implemented incremental compilation in Unity).

I’d be more eager to agree with you before the Live Coding era. I can’t complain now, I’m able to change the logic while the game is running. This is magic. Better than blueprints.

After first launch of the day, here it takes from 16 to 20 seconds to relaunch Unreal Editor after a compilation in Visual Studio…
I think these complaints come from people without SSD and/or using slow CPUs causing a long wait for Editor to open.

Or incorrectly set up projects that load 50000 assets on launch.

My project has currently 75K assets, loading time is usually brief, but out of curiosity, how can you change the project assets loading related setup?

Always set as default a “Test” map with minimal hard references to assets, to boost Editor’s startup :slight_smile:

It’s not viable if you are developing a huge world full of navmesh and other things. But thanks. They should remove hot reload if it’s so broken. I will check back this engine wants it’s more usable.

Well, in case of open worlds, one thing to use now is World Composition which doesn’t load all sublevels used by the opened level in editor.

Fortunately Epic is finally investing in open-world tools. Soon we should have a mechanism for working on the map without sublevels (one world and every asset instance saved separately to the hard drive).
I truly hope they also gonna upgrade the navmesh system. Not much changed in recent years and navmesh can easily grow to gigabytes (if counting for the entire world).