Forgetting to set JAVA_HOME leads to a somewhat cryptic error message.

[odinsbane]

When I try to init pyimagej on osx I get the following error. (truncated!)

File "env/lib/python3.13/site-packages/scyjava/_jvm.py", line 74, in jvm_version
p = Path(default_jvm_path)
TypeError: argument should be a str or an os.PathLike object where fspath returns a str, not 'bytes'

If I point JAVA_HOME at a valid java jdk then I don't get this error.

I think there are two points here:

• It is failing to use a fallback version check because of an unexepected error.
• It doesn't report this error is occuring while trying to find java (though implied in the stacktrace)

Thanks!

[ctrueden]

Based on the information above, I would consider this a bug in scyjava, not pyimagej.

The scyjava code in question here is:

    default_jvm_path = jpype.getDefaultJVMPath()
    if not default_jvm_path:
        raise RuntimeError("Cannot glean the default JVM path")
    print(f"Default JVM path from JPype: {default_jvm_path}")

    # Good ol' macOS! Nothing beats macOS.
    jvm_path = default_jvm_path.replace(
        "/Contents/MacOS/libjli.dylib", "/Contents/Home/lib/libjli.dylib"
    )

    p = Path(jvm_path)

So I guess default_jvm_path is coming back as not-a-str?

With JAVA_HOME unset, what do you see when you run:

import jpype
default_jvm_path = jpype.getDefaultJVMPath()
print(default_jvm_path)
print(type(default_jvm_path))

?

[odinsbane]

It returns a binary string,

b'/Users/username/Library/Java/JavaVirtualMachines/temurin-25/Contents/Home'
<class 'bytes'>

Which is a valid jdk. I think there was an update to pathlib, where it used to accept bytes but now it requires a string or path object. Possibly a work around would be.

default_jvm_path = os.fsdecode(default_jvm_path)

I dont know if jpype.getDefaultJVMPath always returns bytes, or if it is only in certain instances. This will work with strings or bytes on my limited testing.