New article: /p/77

Author: iBug

_posts/2025/2025-07-28-palworld-0.6-resize-guild-chest.md

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+---
+title: "Manually resize Guild Chest in Palworld 0.6"
+tags: games palworld
+redirect_from: /p/77
+---
+
+The Guild Chest, first introduced in Feybreak Update, easily became the best way to move items between bases.
+However, it only has 54 slots and is nowhere near enough for all the items you want to store.
+For those who want to increase the size of the Guild Chest, especially in single player worlds, there's a tutorial on how to do it manually:
+[Guild chest resizer after solo play started (Manual)](https://www.nexusmods.com/palworld/mods/2419).
+
+A few months back, I followed this tutorial and successfully resized my Guild Chest to 270 slots.
+But this time on my friend's save, the script no longer worked.
+
+```console
+PS D:\Downloads\GuildChestResizer> python sav-to-gvas.py D:\Downloads\GuildChestResizer\Level.sav
+Traceback (most recent call last):
+  File "D:\Downloads\GuildChestResizer\sav-to-gvas.py", line 30, in <module>
+    main()
+  File "D:\Downloads\GuildChestResizer\sav-to-gvas.py", line 18, in main
+    uncompressed_data = zlib.decompress(data[12:])
+                        ^^^^^^^^^^^^^^^^^^^^^^^^^^
+zlib.error: Error -3 while decompressing data: incorrect header check
+PS D:\Downloads\GuildChestResizer>
+```
+
+Fortunately, I had my own save file where I performed the steps, so I could investigate the issue.
+
+## Investigation
+
+Notice how the script tries to decompress the data using zlib, with the first 12 bytes skipped.
+So the first thing to check is to compare the header of the save files.
+
+My save file (that worked):
+
+```text
+00000000  7d d3 67 01 c8 51 23 00  50 6c 5a 32 78 9c 64 7a  |}.g..Q#.PlZ2x.dz|
+```
+
+My friend's that no longer works:
+
+```text
+00000000  09 c2 8b 01 a7 f1 20 00  50 6c 4d 31 8c 0a 00 36  |...... .PlM1...6|
+```
+
+According to [Stack Overflow](https://stackoverflow.com/q/9050260/5958455), `78 9c` indicates default compression for zlib, while `8c 0a` is not a valid zlib header.
+After playing around with the save file, I concluded that the save file was not compressed with zlib at all, so time to look for other clues.
+
+By examining the Python script, particularly the "convert back" one (`gvas-to-sav.py`), I figured out the header for the `.sav` file:
+
+- Bytes 0-4: Size of uncompressed data (4 bytes, little-endian)
+- Bytes 4-8: Size of compressed data (4 bytes, little-endian)
+- Bytes 8-11: Magic number (3 bytes, `PlZ`)
+- Bytes 12: Possibly type information, as the script checks for `0x32`
+
+It's easy to notice the discrepancies between the failing save file and the above structure:
+
+- The magic number is `PlM` instead of `PlZ`.
+- The potential type information is `0x31` instead of `0x32`.
+
+The uncompressed size and compressed size fields are correct for that file itself, so most likely the new save file employs a different compression algorithm.
+Time to identify it.
+
+## Finding the compression algorithm
+
+So here comes the trick: I know about this other tool called [PalEdit](https://www.nexusmods.com/palworld/mods/104), which is also written in Python and is [open-source on GitHub](https://github.com/EternalWraith/PalEdit), so it's easy to read the code for clues and insights.
+
+There's a `SaveConverter.py` file that catches my attention, which refers:
+
+```python
+from palworld_save_tools.palsav import compress_gvas_to_sav, decompress_sav_to_gvas
+```
+
+... except there's no `palworld_save_tools` directory anywhere in the repository.
+Though interestingly, there *is* a [`palworld_save_tools.zip` file](https://github.com/EternalWraith/PalEdit/blob/main/palworld_save_tools.zip) in the root of the repository.
+
+Recalling how Python can [execute](https://docs.python.org/3/using/cmdline.html#interface-options) a directory or a zip file if it contains a `__main__.py` script, it sure can *import* it as well if it contains a `__init__.py`, so time to unpack that ZIP archive and inspect the contents.
+Within a few steps you'll land at `compressor/__init__.py` which looks like this at its beginning:
+
+```python
+class SaveType:
+    CNK = 0x30  # Zlib compressed on xbox
+    PLM = 0x31  # Oodle compressed
+    PLZ = 0x32  # Zlib compressed
+
+# [code omitted]...
+
+class MagicBytes:
+    CNK = b"CNK"  # Zlib magic on xbox
+    PLZ = b"PlZ"  # Zlib magic
+    PLM = b"PlM"  # Oodle magic
+```
+
+Now the details become clear:
+The new save file contains `PlM` as its magic bytes and a matching `0x31` type information, so mystery solved and the next step is to figure out how to decompress it.
+
+## Patching the scripts
+
+Searching for `Oodle compression` on Google produces multiple results from Epic Games and Unreal Engine, guess that's their latest feature maybe?
+So I turned my focus back to PalEdit, where there's the `compressor/oozlib.py` file with this:
+
+```python
+try:
+    import ooz
+except ImportError:
+    raise ImportError(
+        f"Failed to import 'ooz' module. Make sure the Ooz library exists in {local_ooz_path} or latest pyooz is installed in your Python environment. Install using 'pip install git+https://github.com/MRHRTZ/pyooz.git'"
+    )
+```
+
+Problem solved, but I'm on Windows without a C toolchain (I no longer do Windows development), so I moved all relevant files onto my Linux server.
+Then it's just a matter of `pip install` command to get the requirements ready.
+
+I also patched the decompressor script:
+
+```python
+#!/usr/bin/env python3
+
+import subprocess
+import sys
+import glob
+import zlib
+import ooz
+
+def main():
+    if len(sys.argv) < 2:
+        exit(1)
+    sav_file = sys.argv[1]
+    with open(sav_file, 'rb') as f:
+        data = f.read()
+        uncompressed_len = int.from_bytes(data[0:4], byteorder='little')
+        compressed_len = int.from_bytes(data[4:8], byteorder='little')
+        magic_bytes = data[8:11]
+        assert magic_bytes == b'PlM'
+        save_type = data[11]
+        assert save_type == 0x31
+        uncompressed_data = ooz.decompress(data[12:], uncompressed_len)
+        if uncompressed_len != len(uncompressed_data):
+            return
+        gvas_file = sav_file.replace('.sav', '.sav.gvas')
+        with open(gvas_file, 'wb') as f:
+            f.write(bytes(uncompressed_data))
+
+if __name__ == "__main__":
+    main()
+```
+
+Now it correctly decompresses my friend's `Level.sav` into `Level.sav.gvas` where I can follow the rest of [the instructions](https://www.nexusmods.com/palworld/mods/2419) manually.
+For compressing the edited file back, I just used the provided `gvas-to-sav.py` file in the belief that the previous zlib-based compression method is still supported by the game.
+
+After sending the edited `Level.sav` file back to the game, we're glad to see our Guild Chest containing 270 slots, which we probably would never use up.
+
+## Postface
+
+If you're on Windows or don't have a C/C++ compiler for installing `pyooz` yourself, the same `palworld_save_tools.zip` provides these files that you may find useful:
+
+```text
+lib/linux_arm64/ooz.so
+lib/linux_x86_64/ooz.so
+lib/windows/ooz.pyd
+```
+
+Of course, how to utilize these files is left as an exercise for the readers.