UnityPy 1.25.0 fails on some Unity 2022.3 bundles with "Invalid version string: 2022.3.62f2", while 1.23.0 works

[com55]

Hi, I found a regression when loading some bundles built with Unity 2022.3.62f2.

Environment

• OS: Windows 11 x64
• Python: 3.12.x
• UnityPy: 1.25.0 (fails), 1.23.0 (works)
• Sample game data source: Stella Sora (Yostar), bundle extension .unity3d

Minimal repro

import UnityPy

env = UnityPy.load("char_11203.unity3d")
for obj in env.objects:
    print(obj.peek_name())

Run Command

PS I:\_CodingWorkspace\test> uv run "i:\_CodingWorkspace\test\test.py"
Error parsing file 'CAB-fc17455868f74b0aa8a95d5b4a3a4a13' as 0: Invalid version string: 2022.3.62f2
2
Error parsing file 'char_11203.unity3d' as 1: Invalid version string: 2022.3.62f2
2
Traceback (most recent call last):
  File "i:\_CodingWorkspace\test\test.py", line 2, in <module>
    env = UnityPy.load("char_11203.unity3d")
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\environment.py", line 63, in __init__
    self.load_file(arg)
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\environment.py", line 152, in load_file
    f = parse_file(reader, self, name=stream_name, typ=typ, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\helpers\ImportHelper.py", line 155, in parse_file
    raise e
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\helpers\ImportHelper.py", line 149, in parse_file
    f = files.BundleFile(reader, parent, name=name, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\files\BundleFile.py", line 53, in __init__
    self.read_files(blocksReader, m_DirectoryInfo)
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\files\File.py", line 82, in read_files
    f = ImportHelper.parse_file(node_reader, self, name, is_dependency=self.is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\helpers\ImportHelper.py", line 155, in parse_file
    raise e
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\helpers\ImportHelper.py", line 147, in parse_file
    f = files.SerializedFile(reader, parent, name=name, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\files\SerializedFile.py", line 273, in __init__
    self.set_version(unity_version)
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\files\SerializedFile.py", line 360, in set_version
    self.version = UnityVersion.from_str(string_version)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "I:\_CodingWorkspace\test\.venv\Lib\site-packages\UnityPy\helpers\UnityVersion.py", line 61, in from_str
    raise ValueError(f"Invalid version string: {version}")
ValueError: Invalid version string: 2022.3.62f2
2

Actual result on 1.25.0

• It fails with:
  • Error parsing file 'CAB-...' as 0: Invalid version string: 2022.3.62f2
  • Error parsing file '...char_11203.unity3d' as 1: Invalid version string: 2022.3.62f2
  • ValueError: Invalid version string: 2022.3.62f2 (sometimes appears as 2022.3.62f2 followed by an extra trailing line/character in output)

Expected result

• Bundle should load successfully (same file works on 1.23.0).

Additional info

• Downgrading UnityPy to 1.23.0 makes the same script and same file run normally.
• This looks like a parsing regression in newer versions for certain serialized data/version string handling.

[com55]

Extra reproducibility details:

• Works on: UnityPy==1.23.0
• Fails on: UnityPy==1.25.0
• Python: 3.12.x
• OS: Windows 11 x64

Quick sanity check:

• UnityVersion.from_str("2022.3.62f2") works in isolation.
• The failure happens when parsing this bundle/serialized file in 1.25.0.
• Error text often shows an extra trailing line/character after 2022.3.62f2 (e.g. "2022.3.62f2\n2"), which may indicate a read/parsing boundary issue.

[isHarryh]

Could you provide a sample file?

[isHarryh]

Cause 1

Commit 807f388 fails this regression.

Before: Use simple number splitting to parse version.

# In UnityPy/files/SerializedFile.py - set_version
def set_version(self, string_version: str):
    self.unity_version = string_version
    # ...
    build_type = re.findall(r"([^\d.])", string_version)
    self.build_type = BuildType(build_type[0] if build_type else "")
    version_split = re.split(r"\D", string_version)
    self.version = tuple(int(x) for x in version_split[:4])

After: Use strict regex to parse version.

# UnityPy/files/SerializedFile.py - set_version
def set_version(self, string_version: str):
    self.unity_version = string_version
    # ...
    self.version = UnityVersion.from_str(string_version)


# UnityPy/helpers/UnityVersion.py
VersionPattern = re.compile(r"^(?P<major>\d+)\.(?P<minor>\d+)\.(?P<build>\d+)(?P<type_str>.+?)?(?P<type_number>\d+)?$")

@classmethod
def from_str(cls, version: str):
    match = VersionPattern.match(version)
    if not match:
        raise ValueError(f"Invalid version string: {version}")  # 👈 Error
    # ...

Cause 2

Somehow the binary parser returns "2022.3.62f2\n2" for your asset file that causes UnityVersion.from_str to fail, in which \n2 is not expected. This may be an issue related to binary readers. Further investigation is available after you provide a sample file. Update: Binary reader is not the cause.

[com55]

Based on the traceback on my side, this looks more likely to be Cause 2: the Unity version string being read contains unexpected trailing characters (e.g. a newline). The error prints as two lines:

ValueError: Invalid version string: 2022.3.62f2
2

which suggests the parsed value is something like "2022.3.62f2\n2" (or \r\n2).

Sample file

char_11203.zip

Repro code

import UnityPy
env = UnityPy.load("char_11203.unity3d")
print("UnityPy.load successful.")

Results by UnityPy version

UnityPy 1.25.0 (fails)

❯ uv pip install UnityPy==1.25.0
Audited 1 package in 3ms
❯ uv run test.py
Error parsing file 'CAB-fc17455868f74b0aa8a95d5b4a3a4a13' as 0: Invalid version string: 2022.3.62f2
2
Error parsing file 'char_11203.unity3d' as 1: Invalid version string: 2022.3.62f2
2
Traceback (most recent call last):                                File "/mnt/ssd/vscode/testUnityPy/test.py", line 2, in <module>                                                                   env = UnityPy.load("char_11203.unity3d")
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/environment.py", line 63, in __init__
    self.load_file(arg)
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/environment.py", line 152, in load_file              f = parse_file(reader, self, name=stream_name, typ=typ, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/ImportHelper.py", line 155, in parse_file
    raise e
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/ImportHelper.py", line 149, in parse_file
    f = files.BundleFile(reader, parent, name=name, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/BundleFile.py", line 53, in __init__
    self.read_files(blocksReader, m_DirectoryInfo)
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/File.py", line 82, in read_files
    f = ImportHelper.parse_file(node_reader, self, name, is_dependency=self.is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/ImportHelper.py", line 155, in parse_file
    raise e
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/ImportHelper.py", line 147, in parse_file
    f = files.SerializedFile(reader, parent, name=name, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/SerializedFile.py", line 273, in __init__
    self.set_version(unity_version)
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/SerializedFile.py", line 360, in set_version
    self.version = UnityVersion.from_str(string_version)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/UnityVersion.py", line 61, in from_str
    raise ValueError(f"Invalid version string: {version}")
ValueError: Invalid version string: 2022.3.62f2
2

UnityPy 1.24.2 (fails)

❯ uv pip install UnityPy==1.24.2
Resolved 12 packages in 22ms
Uninstalled 1 package in 7ms
Installed 1 package in 11ms
 - unitypy==1.25.0
 + unitypy==1.24.2
❯ uv run test.py
Traceback (most recent call last):
  File "/mnt/ssd/vscode/testUnityPy/test.py", line 2, in <module>
    env = UnityPy.load("char_11203.unity3d")
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/environment.py", line 63, in __init__
    self.load_file(arg)
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/environment.py", line 152, in load_file
    f = parse_file(reader, self, name=stream_name, typ=typ, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/ImportHelper.py", line 141, in parse_file
    f = files.BundleFile(reader, parent, name=name, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/BundleFile.py", line 50, in __init__
    self.read_files(blocksReader, m_DirectoryInfo)
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/File.py", line 82, in read_files
    f = ImportHelper.parse_file(node_reader, self, name, is_dependency=self.is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/ImportHelper.py", line 139, in parse_file
    f = files.SerializedFile(reader, parent, name=name, is_dependency=is_dependency)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/SerializedFile.py", line 272, in __init__
    self.set_version(unity_version)
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/files/SerializedFile.py", line 359, in set_version
    self.version = UnityVersion.from_str(string_version)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/mnt/ssd/vscode/testUnityPy/.venv/lib/python3.12/site-packages/UnityPy/helpers/UnityVersion.py", line 61, in from_str
    raise ValueError(f"Invalid version string: {version}")
ValueError: Invalid version string: 2022.3.62f2
2

UnityPy 1.23.0 (works)

❯ uv pip install UnityPy==1.23.0
Resolved 11 packages in 28ms
Uninstalled 1 package in 8ms
Installed 1 package in 16ms
 - unitypy==1.24.2
 + unitypy==1.23.0
❯ uv run test.py
UnityPy.load successful.

[nesrak1]

\n2 after a version is pretty common.

This may be an issue related to binary readers

It's not a parsing error making it read too much, it's just something that gets added to the end of many game versions. Still don't know why. I usually strip everything after f### (or some other character other than f).

[com55]

I just checked the raw bytes of the file header as suggested. Here's what I found:

b'UnityFS\x00\x00\x00\x00\x085.x.x\x002022.3.62f2\x00\x00\x00\x00\x00\x00\x01\r\xa7\x00\x00\x00J\x00\x00\x00e\x00\x00\x02C\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x1e\x00\x01\x000\x02\x00\x02\x07\x00\xc0\xb9\xda\x00\x03\x00\x00\xef\x0f\x00\x00S=\n\x00*\x00\x01&\x00\x00\x1a\x00\xf0\x18\x00\x04CAB-fc17455868f74b0aa8a95d5b4a3a4a13\x00\x00\x00\x00\x00\x00\x00\x16\x00\x01\x00\x16\x16\x0b\x00!\x85!\x07\x003\x02\xef\x0f\x10\x00\x14`\x1a\x00\xf0\x002022.3.62f2\n2\x00\x13\x13\x00P\x14\x00\x00\x00s\t\x00\xf1\x04\xff\xff\x1e\xf1'

There are two version strings in the header. The first one is standard, but the second one confirms @nesrak1's suspicion:

# Raw bytes from the header
...2022.3.62f2\x00... # First instance (Normal)
...2022.3.62f2\n2\x00... # Second instance (Problematic)

In UnityPy 1.25.0, this \n2 at the end of the version string seems to break the loader, while UnityPy 1.23.0 handles it without any issues.

This is definitely a regression in how the binary reader or the version parser handles trailing characters/newlines in the version string. It would be great if the parser could be updated to strip or ignore anything after the build-suffix (like f###), as mentioned by @nesrak1.

[isHarryh]

I checked the file and found that the version string for the serialized file is indeed "2022.3.62f2\n2".

---

In AS's implementation, they treat any non-numerical characters as splitter:

// AnimeStudio/SerializedFile.cs - Line 244
public void SetVersion(string stringVersion)
{
    if (stringVersion != strippedVersion)
    {
        unityVersion = stringVersion;
        var buildSplit = Regex.Replace(stringVersion, @"\d", "").Split(new[] { "." }, StringSplitOptions.RemoveEmptyEntries);
        buildType = new BuildType(buildSplit[0]);
        
        var versionSplit = Regex.Replace(stringVersion, @"\D", ".").Split(new[] { "." }, StringSplitOptions.RemoveEmptyEntries);
        version = versionSplit.Select(int.Parse).ToArray();
    }
}

Implementation	Success?	Result
AnimeStudio	✓	buildType='f\n', version=[2022, 3, 62, 2, 2]
UnityPy 1.23	✓	buildType='f', version=(2022, 3, 62, 2)
UnityPy 1.25	✗	ValueError: Invalid version string: 2022.3.62f2\n2

Conclusion

Version string trailing with \n and a number can happen. Former version of UnityPy can handle this normally while recent version of UnityPy failed to do that due to strict regex parsing.

[K0lb3]

Sorry, I was on vacation.
I pushed a fix just now.

The UnityVersion class is more or less a clone of the AssetRipper version and I totally forgot about the optional postfixes.
I re-added support for them now and also included them in the tests, so this issue shouldn't happen again.

Also, thanks for posting the issue and the discussion.