4.8.1 ERR: Transient text cannot be serialized

I’m getting over 892 “ERR: Transient text cannot be serialized” errors in my log file when I startup. After a few days of troubleshooting I found the following causes for them.

Transient Bug #1
-If you Split Pin any structs instead of Breaking them, Each exposed variable become a transient error. A quick repro is to use the level blueprint and create a few of these split structs and watch your log file. My work around was to go back and redo my nodes to use break and make nodes. This reduced me to 522 transient errors.

Transient Bug #2
-If you use “Blend Pose by Int” inside of the AnimationBlueprint, each blend pin plus any extra that you add creates several transient errors. Currently, I don’t have a work around for this besides not using the nodes.

There are definitely a few other animation nodes that give this transient error which i have yet to track down.

Please look into this matter, thanks! =)

Just to clarify, we started getting these 892 transient text errors only after upgrading from 4.7.6 to 4.8.0.


  1. Create a new project, third person template
  2. In the Level BP, spawn an actor on begin play using SpawnActor BP node
  3. Right click on the SpawnTransform pin and select “Split Struct Pin”

Run the game in Standalone with logging active, and notice the appearance of ERR: Transient text cannot be serialized for all the split SpawnTransform pins.

It’s a really simple repro, and the log shows the errors each time you play the game in standalone. If you need a repro project I can supply one



Transient Bug #3
–Blend by bool in the Animblueprints also cause transient errors just like their int cousin

We are also seeing this for nodes added in the AnimGraph states. In our cases it is a warning and not an error. Also happened after moving to 4.8

I have also those warning logs like:
ERR: Transient text cannot be serialized “False Blend Time”.

I’m getting the same “Warning: ERR: Transient Text cannot be serialized” over 100 occurrences before my Standalone crashes and starts the UE4 Crash Reporter - with an “Unhandled Exception: EXCEPTION_ACCESS_VIOLATION” as the breaking point.

Hey Everybody,

Thanks for reporting this. I have entered this bug as UE-18174.


Was this issue addressed yet? We are trying to narrow down causes for a crash and was not able to find it in 4.9 or 4.10 release notes as a fix.

It was not marked in the release notes because the bug was no longer reproducing in 4.9. When something is fixed, but we don’t know the particular changelist that fixed it, you may not find it in the Release Notes.

Yeah I figured as much. Much appreciated.