What causes AutomationTool exit code 25 in Unreal build pipelines?

UAT's generic 'a step failed' exit — the real failure (compile error, cook error, signing, stage/deploy problem) is upstream in the log, commonly on CI where environment differs from dev machines.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix AutomationTool Exiting With Code 25 During Unreal Packaging

Quick answer: Read the UAT log backwards from the exit to the first failing step, fix that step (build, cook, or stage), and make CI environments match the toolchain the editor uses.

Exit 25 tells you 'something failed', nothing more. Treat it as a pointer into the log. The differences between CI and a working dev machine are the usual root cause. Here is the diagnostic order.

How to fix it

1. Locate the failing step

UAT logs each phase (Compile, Cook, Stage, Package, Archive); the first phase reporting errors is your actual problem — the exit code is just the messenger.

2. Diff the environment

CI failures with local success mean toolchain drift: engine version, Visual Studio/MSVC components, Windows SDK, Android NDK — pin versions explicitly on the agent.

3. Run the same command locally

Copy the exact RunUAT command line from CI and run it on a workstation — reproducing outside CI cuts iteration from minutes to seconds.

4. Fail loudly in the pipeline

Configure CI to surface the UAT log tail (or upload the log artifact) on failure so nobody debugs from the exit code alone again.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unreal Engine error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

Reproduce it once with full context and the fix writes itself. The hunt is the expensive part.