I have been lost at sea for 9 months now...

*My Dearest Epicmilia, *

You use to comfort me in your arms late at night and sing me to sleep, your angelic voice ensured me everything was going to be alright.
I embrace those thoughts now as the cold sea rocks me to sleep. I wake up with crusty eyes and saltwater lips, just to find I am still alone in this wooden sarcophagus.
I remissness of my days with you, these are the days I miss the most. I was but a mere child watching my parents every move. I learned from you, I looked up too you, and now I fear I am becoming you.
What becomes of life when the child becomes the parent. Nothing good I presume… It is what I feared, everything I learned, everything I am … has bin reverted to you.
I scream at the mirror because I share your likeness, I am no longer a unique personality, I have lost touch with the variables that made me, ME !
Please help me Epicmilia…You’re my only hope…

okay in all seriousness… Epic can you please fix child blueprints being reverted to their parents, I paid good money for marketplace items that are being rendered useless due to this bug I have experienced since 4.7 ]

In all seriousness, what child blueprints are you referring to?

All child blueprints, one example would be generic shooters base weapon, any child of it will have it’s guns sounds and variables reset on either restart or build.

That’s normal and is working as intended. Any problems with it?

No it is not working as intended, No it is not normal…from Allars mouth " This is a known UE4 BUG " Another reference [Bug] Child blueprint values resetting on editor restart - UE4 AnswerHub -
Another reference ? [Bug Report][Reproducible] Child Actor Component's Class clears on editor restart - UE4 AnswerHub ANOTHER REFERENCE Child Actor Component's Class clears on editor restart - UE4 AnswerHub — As you can see this bug dates back to Unreal Engine 4.7 and is still happening today on 4.10 - So you can see why I am getting a little impatient here.

This has been an ongoing issue that can make large scale blueprint projects simply… unshippable. There are some crazy workarounds and every engine update the issue seems to be resolved a little bit more but still ever present. Its happening across all projects with multiple independent people encountering it, see Elephantiasis’ post for references.

The Situation:

Say you have a BP class called Person.
You then have a child class of Person called Walter White.
You then have a child class of Walter White called Heisenberg.

Say Person has two variables, one called “Chemistry Skill” and one called “Drug Selling Skill”.

By default, Person has both of these set to 5.
By default, Walter White has “Chemistry Skill” set to 100 but “Drug Selling Skill” set to 10.
By default, Heisenberg has “Chemistry Skill” at its parent default of 100 but “Drug Selling Skill” set to 100.

**The Issue:

**Infrequently, but not rare, when you load your project in the UE4 Editor (or sometimes even the cooker) you will find that without any changes you’ll see both Walter White’s and Heisenberg’s “Chemistry Skill” and “Drug Selling Skill” become set to 5, the defaults of the class’s most base class short from C++.


This can cause an entire project’s skill tree system, weapons, characters, level actors, AI, and any other system that depends on the use of child classes to suddenly be ‘reset’. Child classes are a huge part of development within UE4 and the last thing you want is for them to be unreliable. The worst part about this is because it happens what appears to be randomly, you can never anticipate this or mitigate it effectively.

**Current Fix:
**While it is unknown as to how to prevent this from happening, you can mitigate the damage if you are using Perforce. Close the editor, check out the affected blueprints out then immediately revert them, and reload the project. (notice the checkout here, no changes were made to this file yet it loads with its values reset. Some how by doing this (possibly changing the asset’s timestamp and thus its load order?) it will mitigate the bug until the next time it happens.

If you have a large project and you aren’t using Source Control and this bug hits you, may @Tim_Sweeney have mercy on your soul.

Wow. I did not even know this problem existed. So no workarounds outside of source control? And how do you even detect if values were reset unless you run into a bug?

Me neither.
I tend to explicitly set variable default values in the actor construction script. I never rely on the values from the details panel…

Yeah, its an old habit i should start relearning now i guess…

****, that explains few things here and there!

Aye, there is no indication that anything happened other than you start seeing ‘default values’ for things that shouldn’t be default. If you have a large project with many smaller classes that affect things in subtle ways… you should probably move to C++ at the moment.

I have the probably all the time in my projects and its extremely frustrating, especially when you have many many different variables with specific values.

Hi Guys,

I just did a quick scrape through our bug database and I’ll say that the known issues with these symptoms appear to have been fixed. Either my search-fu is off and I couldn’t find the existing bugs we have, or we haven’t logged new ones to reflect new ways to reproduce it. That said, if you’re still encountering this, please get us a detailed repro so we can investigate (preferably though something like answer hub). We takes these bugs, and data loss in general, very seriously.

I want to be as transparent as possible here, these sort of issues are usually the symptom of a complicated parent/child cyclic load bug. Our loading code is intricate, and intertwined Blueprint dependencies further complicate the system. Without going into too much detail, in the past this has occurred because the Blueprint’s parent wasn’t being fully loaded until after the child - this is obviously a problem when you rely on that parent’s values (those values would then be copied over to the child, after that child had already been serialized).

This all said, we were pretty confident that we’d fixed this sort of problem. This sounds like a “new” exciting bug that causes the same symptoms. So please, even if it seems like a known bug that others are reporting, please still report it to us yourself. At the very least, this will further escalate the existing issue.

Lastly, because these bugs can take a while to sort out, I always suggest vetting your content as a workaround in the meantime. Cyclic dependency bugs are a headache, so being mindful of the dependencies up front can pay dividends while we try to correct the issues in the engine. Overly complicated/interdependent content can not only expose short comings like this, but slows down iteration times as well. Compiling one Blueprint that a million others depend on, invalidates those and requires that we compile those as well.

I look forward to having a repro for this so we can investigate these for you guys. And thanks for bringing this to our attention. Posts like this (and ones on answer hub), are what keeps us up to date on issues that we don’t encounter in our own day-to-day development.

If you want a repo, ask allar to give you Generic shooter, start a fresh project, create a child blueprint from base_weapon, set the guns sound to something different, save and close project. Reopen and more than likely the child will have bin reverted. There is no way in H E double hockey sticks I am adding another question to the unorganized orgy known as answer hub. I believe if this bug was fixed, Allar would have updated his project because I am sure he is sick of hearing about it. The same scenario has been happening since 4.7 as i have mentioned. I made this forum to get more attention about this reoccurring problem. Have a talk to whoever marked this issue as solved, I am sure it is still happening and just flying under a lot of peoples radar. I am the one who knocks.

Hey folks,

Reiterating what Mike said, if you would please log a bug report on the UE4 Answerhub with repro steps, we will investigate, confirm, and work to resolve the issue as soon as possible. We certainly aren’t aware of any single issue regarding this which has been around for 9 months. The Answerhub posts that were linked to are associated to JIRAs which have been marked as fixed.