event dispatcher mobile preview and device UMG


I’m running engine latest preview tag (4.6).

I have found a mismatch between play in editor and mobile preview / device.

Use case:
Create an UMG widget (parent). This widget creates other UMG widgets (childs).

The childs widgets intend to communicate with the parent widget using a Call to event dispatcher which the parent exposes and binds to a custom event.

This works flawless in Play in Editor / New editor window. But fails in mobile preview editor. I can see this in the log:

[2014.11.10-21.11.12:985][115]LogBlueprint:Error: [compiler] Error Could not find an event-dispatcher named "InventoryItemClickedDispatcher" in 'Inventory_C'.
Make sure 'Inventory_C' has been compiled for  Call InventoryItemClickedDispatcher

Howdy Dredok,

Thank you for reporting this issue. I have been attempting a reproduction of the issue and have been unsuccessful so far. Here is how my Blueprint Widgets set up:

Please let me know if you have your BP’s set up any differently then mine currently are. I have been testing on the currently release 4.5.1 and later build of the engine and have been able to play on mobile preview with no issues.

Thanks and have a great day!

Hi Sean,
I have had many issues with UMG widgets and finally I have setup all my event handlers to being housed in a separate BP (a persistent actor BP injected on those widgets which need to communicate). However I will try to setup a fail scenario this weekend and will share with you.

Howdy Dredok,

Just wanted to check in with you and see how the testing over this weekend went. Please let me know if you ran across the same issue.

Thanks and have a great day!

I’m sorry for the late answering … I haven’t had time to setup this till now. The problem occurs when you pass references between the widgets. I attach a example which do not work (using latest promoted branch engine source).

It works on Standard editor but do not work on Preview mobile (and I guess it will not work either in android device).

alt text


Hey Dredok,

In the Parent Graph, I am a bit lost as to how you got the Parent input on the Create Child_C Widget node. I have the rest of the graph setup and this would be the last piece that i need.

Thanks and have a great day!

in the child graph, on the parent variable, check “Expose on Spawn” and it will appear the input in Create Widget


Howdy Dredok,

I have been able to setup the example but i have been unable to see any error occur within the project. Would you be able to send me and example project so that i may be able to further investigate the issue?

If you would like, you can send me the example project to me over the forums via a private message. Here a link to my profile page: https://forums.unrealengine.com/member.php?4890-Sean-Gribbin


Did you test it on mobile preview?

I did upload an example project to dropbox

Thank you sharing the example project. I have tested on mobile preview but was unsuccessful in seeing the issue you have been. I will download your project now.

Howdy Dredok,

Thank you again for sending that test project over. I was able to see the issue occurring very easily. I have gone ahead and written bug report UE-5799 and placed it into our bug database so that it may be addressed in a future release.

Thanks again and have a great day!

is this related? EventDispatcher in GameMode broken on 4.6? - Community & Industry Discussion - Unreal Engine Forums

Could be. Your eventdispatcher works in editor ?

Just wanted to keep everyone updated. We do have a fix in for the 4.6.1 hotfix to fix multiple issues with the EventNode dispatchers. I am unsure as to when this will be released, but the fix has been implemented.

If you do not see a fix for this issue on that hotfix, please be sure to let me know so that i may further investigate.

Thanks and have a great day!

thats great!
Is this in the promoted branch? or any plans to release it there soon? Because I’m locked in 4.7 version and can not go back without a lot of effort :confused:

Hey Dredok,

Since this feature has been implemented into the 4.6.1 hotfix already, it should be in the promoted branch. You may encounter issues with the promoted branch, though, as it is an unstable build. The 4.6.1 hotfix should be released sooner rather then later, but I am unsure of an exact time at this moment.