4.7.1 Blueprint Function Library unable to save

4.7.1 Binary, as downloaded from launcher

#Build Version:

#Description of Issue
Cannot save Blueprint Function Library with any function that calls another function in the same library. The following error message is reported:

Can’t save …/…/…/…/…/…/Users/User/Documents/Unreal Projects/TestUpdateProject/Content/THIS_IS_THE_PROBLEM.uasset: Graph is linked to private object(s) in an external package.

External Object(s):


Try to find the chain of references to that object (may take some time)?


The function library simply needs to be set up as in the following screenshot to cause this issue

Reproduction Steps

  1. Create a new Blueprint Function Library.
  2. Create two functions in the function library, “Foo” and “Bar”.
  3. Make the function “Foo” call the function “Bar”.
  4. Save and close the project.
  5. Re-open the project
  6. The function library will be unable to save, giving error above.
  7. Delete the call to the function “Bar” from the function “Foo”.
  8. The function library will now be able to save.
  9. Close and re-open the project
  10. The function library will once again be unable to save.


The attached [zip file][2] contains a function library that reproduces the issue in a blank project.

Hi SuddenlyMuffins,

Thanks for the report! I was able to reproduce this in 4.7.1 as well as our internal build, and I have entered a bug report for the developers (UE-11185). I’ll let you know when I see any update on its progress. Thanks!

I would really love to see this fixed. I’ve been seeing this bug pretty regularly the last few days – sometimes even in blueprints that I’m not modifying.

I know it’s being looked into currently, and it’s considered a Critical bug, so hopefully we’ll see a fix soon. I will update this post when I see progress on it. I have added a note that this is occurring for more people, as well. Thanks for your patience!

Thank you Ben, It’s good to hear this is known and being fixed.

Would you mind poking someone about this issue also related to function libraries? I can send a project download link if necessary.

I have had this issue since 4.3 if im not mistaken. not sure if it helps but all the more info right…
I’m now up to having to replace over 100 connections after opening my project because of this… here’s what I do to make life a little less stressful…

  1. use reroute nodes on either side of all function calls that go to the same blueprint(so you can quickly make sure you have them re-pinned correctly)

  2. comment all said function nodes as (Corruptable) of something similar so you can do a Ctrl-F and run a quick search for them all)

also notes on things I have found running a text comparison the only differences I notice before and after the reboot/ replacement is…

gets changes to…
and the pin numbers change to a much lower value however copy pasting back in to blueprint does not fix… pasting in to a text editor and correcting he above line and pasting back in to the editor does correct the issue. leading me to believe this is in fact the issue.

note only the REINST needs changed to default to save but it seams the _0 at the end will still cause a compile warning stating that Default_NewFunctionLibrary_C_0 cannot be found… refreshing the nodes seams to correct the compile warning however…

after going back and testing it is only easily reproducible on 4.7 however as I said it has been happening for some time previously (do to its semi random nature I attributed it to a mem leak though this no longer seems to be the case.

nothing in here is a proper answer as it still require 30 min to fix every time the project is opened… not sure why it was marked answered…

It’s marked as Resolved because a bug report has been put into our system. Once we have an update on it, we’ll post here.

o ok cool :slight_smile:

Hi all,

This has been fixed in our internal build, and the fix should be included in the 4.7.3 release coming soon. Thanks for your patience! Please let us know if the issue is not resolved after upgrading to 4.7.3.

Is this also a fix for this?

It’s possible, but without a solid reproduction for the issue in that post I can’t be sure. It’s certainly worth trying again once 4.7.3 is released.

Are there some specific commit SHA #'s you can post so we can pull down the commits in our 4.7.2 build?? I have the same bug and it was reported that the following commits addressed it:

c9aa7ac0c080c10204ed1eaa5839f017ac1609e3 and

However, I still get the error so I’m wondering if there are more commits to get!

Hey jeffvoight,

Should be this commit:

I’ve been getting this issue as well. I am using 4.7.0 and added the above changes to the engine, completely rebuilt the engine, and still got errors, though the error message has changed slightly.

Old Error message: Warning Can’t save …/…/…/…/…/…/Unreal Projects/MageMaster2/Content/Assets/FuncLib.uasset: Graph is linked to external private object (unknown culprit) (unknown property ref)

New error message: Warning Error saving ‘…/…/…/…/…/…/Unreal Projects/MageMaster2/Content/Assets/FuncLib.uasset’

Can you try opening a copy of the project in 4.7.3 and see if it occurs there as well? Thanks!