Perforce P4 for Unreal Engine

What it is

Perforce P4, formerly Helix Core, stores the shared project in a central depot. Each person syncs a workspace, opens files for edit, and submits a numbered changelist back to the server.

Blueprints and maps are binary packages. Two edits to BP_Player or Persistent.umap usually need someone to choose a revision and reapply the other changes by hand.

With the +l file type, P4 rejects a second checkout of the same depot path. Set that type before adding Unreal assets. P4 Cloud provides managed hosting; a self-managed server needs someone responsible for configuration and backups.

With Unreal Engine

Unreal Editor supports P4 directly. With the correct typemap, .uasset and .umap files use exclusive open, which rejects a second checkout of the same depot path.

Where it fits

How it works

Depot and workspace

A depot holds the shared files and their history. A workspace maps depot paths to folders on one machine. P4 Cloud hosts the server, but each contributor still needs a workspace that includes the project.³¹⁵¹⁶

Changelists

A numbered changelist groups related adds, edits, and deletes. The submit is atomic, so either every file reaches the depot or none of them do. A useful changelist can contain BP_Inventory, its input action, and the config change needed to use it.³

Typemap and exclusive open

The typemap tells P4 how a file pattern behaves. The +l modifier allows only one person to open a depot path for edit at a time. It does not stop someone from changing an already writable local copy outside the normal checkout path. It's ideal to install the Unreal typemap before adding Content, because changing it later means correcting files already in the depot. World Partition levels that use One File Per Actor store each actor in its own package, so two people can lock different actors in the same level.^1291317

Streams and shelves

Streams describe related lines of development and how changes move between them. Shelving uploads pending files without submitting them. Another user cannot normally unshelve an exclusively locked file while its lock remains, but p4 print with the @=change selector can copy the shelved content out for inspection.⁴¹⁰¹²

Protections and recovery data

Server protections decide which users and service accounts can read, open, submit, or administer depot paths. Checkpoints and journals preserve metadata, while versioned file archives hold the project content. Recovery needs both.⁶⁷¹¹¹⁴

In production

1. 01

   Sync a known working revision

   Sync the project before editing BP_Player. UnrealGameSync can show good and bad changelists and download precompiled editor binaries, so artists can choose a revision that has passed the team's checks.

2. 02

   Check out assets before editing

   Connect the editor to the workspace and test checkout with a real .uasset. P4 makes the owner's workspace copy writable and rejects a second open of that depot path. If a second checkout succeeds, stop and fix the typemap before importing more work.¹²⁹¹³

3. 03

   Keep one purpose per changelist

   Move related files out of the default changelist and describe the change. "Fix inventory focus after drop" identifies the work for a reviewer and makes it easier to find later.

4. 04

   Shelve work that needs another pass

   Shelve a risky map, Blueprint, or source change before submit. A reviewer can inspect an exclusively locked shelf with p4 print. Release or transfer the lock before another user tries to unshelve that file into a workspace.¹⁰¹²

5. 05

   Validate before submit

   Reconcile offline work, resolve incoming text changes, check for unintended generated files, and run the relevant editor or build validation. Submit only after the changelist contains the source and assets needed to reproduce the change.

Best practices

Install the typemap before content arrives

Map .uasset, .umap, .ubulk, and other non-mergeable packages to binary+l before the first add. A later typemap change affects only new files. Correct an existing file by opening it with the intended -t type and submitting that revision. The p4 reopen -t command only changes a file that is already open.⁹¹³

Use case-insensitive server mode for Unreal projects

Epic recommends a case-insensitive P4 Server to avoid integration problems with its tools, including UnrealGameSync. Decide this when the server is created instead of discovering path-case differences after the depot is populated.¹⁸

Keep generated data out of the depot

Start from Epic's P4IGNORE rules, then test reconcile on a clean workspace. DerivedDataCache, Intermediate, Saved, and local IDE output create churn without preserving project source.

Treat a changelist as one reviewable change

Keep the map, Blueprint, config, and source needed for one result together. Shelve that changelist for review or handoff instead of sending loose files or mixing unrelated fixes into the same submit.

Publish known-good revisions

Use UnrealGameSync badges or build results to identify changelists that compile and open. Store precompiled editor binaries in the separate location configured for UnrealGameSync.

Test restores on a schedule

Back up depot archives, metadata checkpoints, rotated journals, and the configuration needed to rebuild the service. Verify archive digests and restore into a separate environment on a schedule.⁶⁷

Gotchas

The typemap is not retroactive

Changing a typemap does not correct files already submitted with the wrong type. Open each affected file with the intended type and submit it to record the correction.¹⁹¹³

P4IGNORE matching differs from .gitignore

The syntax is similar, but the matching rules differ. Copying a Git ignore file without testing can leave generated folders visible to reconcile or hide files the build needs.¹

Locks don't cover other streams

Exclusive open protects one depot path. Separate stream paths can still carry different revisions of the same Unreal asset and collide when changes integrate later.²⁴

A checkpoint does not contain depot files

Checkpoints and journals recover server metadata. They do not replace backups of the versioned file archives, so a metadata-only backup cannot restore the project after storage loss.⁶

Writable flags affect builds

Engine source and precompiled-binary workflows depend on correct P4 file types and writable modifiers. A mismatch can appear as an access-denied build or update failure rather than an obvious source-control error.¹⁵

Secure defaults can break old automation

P4 Server 2026.1 enforces authentication and removes implicit user behavior. Scripts that depend on unauthenticated access, automatic user creation, or passwordless login need explicit users, credentials, and p4 login before the upgrade.¹⁴

Adoption checklist

• Choose a stream or classic depot model, then document how release work branches and integrates.
• Install Epic's typemap before adding Unreal assets.
• Add a P4IGNORE file for DerivedDataCache, Intermediate, Saved, and local IDE output.
• Back up both depot archives and server metadata, then test restoration.
• Define who can break locks, administer protections, and recover abandoned workspaces.
• Decide whether UnrealGameSync and precompiled editor binaries belong in the pipeline.
• Run P4 Server in case-insensitive mode for the normal Unreal and UnrealGameSync workflow.
• Use explicit users, authenticated service accounts, and a reviewed protections table.

Related guides

• Git with Git LFSGit version control with separate storage for large files and optional file locking.
• Unity Version ControlVersion control formerly called Plastic SCM, with Smart Locks, a partial-workspace client for artists, and a built-in Unreal provider.
• LoreEpic Games' open-source version control for large binary repositories, currently in pre-stable release.
• DiversionHosted version control with an Unreal Editor plugin and file locks.

Sources

Official sources checked September 24, 2026.

1. 1Unreal Engine Perforce guidedev.epicgames.com
2. 2Perforce exclusive lockinghelp.perforce.com
3. 3Perforce workspaces and changelistshelp.perforce.com
4. 4Perforce streamshelp.perforce.com
5. 5UnrealGameSync referencedev.epicgames.com
6. 6Perforce disaster recoveryhelp.perforce.com
7. 7Perforce archive verificationhelp.perforce.com
8. 8Epic Education guide to version controlcdn2.unrealengine.com
9. 9P4 typemap referencehelp.perforce.com
10. 10P4 shelving referencehelp.perforce.com
11. 11P4 protections referencehelp.perforce.com
12. 12P4 unshelve referencehelp.perforce.com
13. 13P4 file type modifiershelp.perforce.com
14. 14P4 secure-by-default updatehelp.perforce.com
15. 15Perforce P4 naming updateperforce.com
16. 16Perforce P4 Cloudperforce.com
17. 17One File Per Actordev.epicgames.com