dotnet/runtime · error · RuntimeError

Unsupported OS.

Error message

Unsupported OS.

What it means

Raised by SuperPMICollect.__init__ in superpmi.py when coreclr_args.host_os is not 'osx', 'linux', or 'windows'. The constructor uses host_os to pick the collector shim name (libsuperpmi-shim-collector.{dylib,so,dll}) and corerun tool; an unrecognized OS has no shim mapping.

Solutions

1. Pass -host_os as exactly osx, linux, or windows.
2. Let the script auto-detect by omitting -host_os.
3. Confirm the collector shim for your OS actually exists in Core_Root before relying on it.

Example fix

// before
python superpmi.py collect --core_root <r> -host_os darwin 'cmd'   # 'Unsupported OS.'
// after
python superpmi.py collect --core_root <r> -host_os osx 'cmd'

SUPPORTED = {"osx", "linux", "windows"}
if host_os not in SUPPORTED:
    raise SystemExit(f"collect requires -host_os in {sorted(SUPPORTED)}, got {host_os!r}")

def is_supported_collect_os(s: str) -> bool:
    return s in {"osx", "linux", "windows"}

When it happens

Trigger: Running `superpmi.py collect` with -host_os set to an unsupported/typo value, or on a host whose detected OS string the script does not recognize.

Common situations: Capitalized OS strings; using 'mac'/'darwin' instead of 'osx'; running on FreeBSD/other; misconfigured host_os override.

Related errors

• Expected a '.ilc.rsp' file for nativeaot, but got
• Pass only one tiering option.
• Tiering options have no effect for nativeaot collections.
• Tiering options have no effect for pmi or crossgen2…
• Unable to find input file in

AI-assisted analysis of dotnet/runtime@60108ba66e (2026-08-10). Data as JSON: /api/errors/c495c8ae29d59776. Report an issue: GitHub.

Appendix: source

Thrown at src/coreclr/scripts/superpmi.py:693

        Args:
            coreclr_args (CoreclrArguments) : parsed args

        """

        self.core_root = coreclr_args.core_root

        if coreclr_args.host_os == "osx":
            self.collection_shim_name = "libsuperpmi-shim-collector.dylib"
            self.corerun_tool_name = "corerun"
        elif coreclr_args.host_os == "linux":
            self.collection_shim_name = "libsuperpmi-shim-collector.so"
            self.corerun_tool_name = "corerun"
        elif coreclr_args.host_os == "windows":
            self.collection_shim_name = "superpmi-shim-collector.dll"
            self.corerun_tool_name = "corerun.exe"
        else:
            raise RuntimeError("Unsupported OS.")

        self.collection_shim_path = os.path.join(self.core_root, self.collection_shim_name)

        jit_name = get_jit_name(coreclr_args)
        self.jit_path = os.path.join(coreclr_args.core_root, jit_name)

        self.superpmi_path = determine_superpmi_tool_path(coreclr_args)
        self.mcs_path = determine_mcs_tool_path(coreclr_args)

        self.collection_command = coreclr_args.collection_command
        self.collection_args = coreclr_args.collection_args

        if coreclr_args.pmi:
            self.pmi_location = determine_pmi_location(coreclr_args)
            self.corerun = os.path.join(self.core_root, self.corerun_tool_name)

        if coreclr_args.crossgen2:
            self.corerun = os.path.join(self.core_root, self.corerun_tool_name)

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