When packaging a project for Mac with UE 5.8, AutomationTool reads a valid non-zero chunk manifest (“pakchunk111.txt”) but generates a “PakCommands.txt” file containing only the chunk-0 command. UnrealPak then creates only “pakchunk0-Mac.pak”, even though the cook/stage pipeline reports two chunks and the chunk-111 cooked files are present in the pre-Pak staging manifest.
The same repro project produces “pakchunk111-Mac.pak” in UE 5.4. UE 5.8 Windows packaging also creates its non-zero chunk Pak, so this seems specific to the UE 5.8 packaging on Mac.
Environment:
- macOS 26.5.2 (25F84), Apple Silicon (Mac14,9)
- UE 5.4 Launcher build: “++UE5+Release-5.4-CL-35576357”
- UE 5.8 Launcher build: “++UE5+Release-5.8-CL-56702186”
- Target: Mac, Shipping
- Project path for clean repro: “/private/var/tmp/PakTestContent58”
- Project packaging settings:
- Use Pak File: enabled
- Generate Chunks: enabled
- Use Io Store: disabled
- Use Zen Store: disabled
- Compression: enabled
I tried tracing through some of the build process and this is what I found
The package command succeeds with exit code 0, but only “pakchunk0-Mac.pak” is generated.
The log shows that AutomationTool successfully reads both chunk manifests:
```text
Reading chunk list file …/pakchunklist.txt which contains 2 entries
Reading chunk manifest …/pakchunk0.txt which contains 494 entries
Reading chunk manifest …/pakchunk111.txt which contains 5 entries
```
It then calls UnrealPak with “-CreateMultiple=…/PakCommands.txt”, but the generated “PakCommands.txt” contains only:
```text
“/private/var/tmp/PakTestContent58/Saved/StagedBuilds/Mac/PakTestContent/Content/Paks/pakchunk0-Mac.pak” -create=“…/PakList_pakchunk0-Mac.txt”
```
There is no command for “PakList_pakchunk111-Mac.txt”. So UnrealPak only loads the chunk-0 response file and creates only “pakchunk0-Mac.pak”.
The chunk-111 assets are present in “PrePak_Mac_UFSFiles.txt”, and the chunk-0 Pak receives all 2,838 pre-Pak UFS entries. This seems to indicate that the failure happens between reading the chunk manifests and generating the CreateMultiple commands, not during cooking or UnrealPak execution.
“DA_PakTest” itself is cooked but assigned to chunk 0 in UE 5.8, despite its PrimaryAssetLabel settings. In UE 5.4 it is in chunk 111. This occurs on Windows as well, so it appears separate from the Mac-only missing-Pak issue.
For comparison, I also tried doing it with Unreal 5.4, and it:
- reads two chunk manifests (370 packages in chunk 0; 6 packages in chunk 111);
- writes two lines to “PakCommands.txt”;
- loads “PakList_pakchunk111-Mac.txt”;
- creates “pakchunk111-Mac.pak” with 14 entries.
In UE 5.8, the chunk manifest syntax also differs:
```text
UE 5.4: \private\var\tmp\PakTestContent54\Saved\Cooked\Mac\…
UE 5.8: ..\..\..\..\private\var\tmp\PakTestContent58\Saved\Cooked\Mac\…
```