How to Fix an Unreal Engine Mod .pak Not Mounting at Runtime

Your game scans a Mods folder and finds a .pak, but its blueprints and assets never appear. Unreal will not surface paked content until the pak is mounted at the right virtual path and the AssetRegistry is told to scan it.

How to fix it

1. Mount the pak file explicitly

Use the pak platform file layer (or the I/O store equivalent) to mount the .pak. Cooked mod content built as a plugin can also be mounted via IPluginManager::MountExplicitlyLoadedPlugin.

2. Register the correct mount point

Mount the pak's content to the virtual path the assets were cooked under, e.g. /Game/Mods/MyMod/. A mismatch between cook path and mount point makes every reference fail to resolve.

3. Scan the path in the AssetRegistry

After mounting, call AssetRegistry.ScanPathsSynchronous on the mounted directory so the registry indexes the new assets. Without this, FindAssetData and async loads return nothing.

4. Match engine and cook settings

Mods must be cooked with the same engine version and target platform as the game. A pak cooked with a different version fails to mount or loads corrupt objects.

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.