What causes "Failed to enumerate results." in java-native-access/jna?

Inspect the HRESULT inside the COMException (getHresult()) and match it against Wbemcli constants to find the specific cause.

java-native-access/jna · error · com.sun.jna.platform.win32.COM.COMException

Failed to enumerate results.

Error message

Failed to enumerate results.

What it means

In enumerateProperties, any HRESULT from IEnumWbemClassObject::Next that is not WBEM_S_FALSE / WBEM_S_NO_MORE_DATA / WBEM_S_TIMEDOUT and indicates failure (COMUtils.FAILED) produces this COMException, wrapping the HRESULT for diagnostics.

Source

Thrown at contrib/platform/src/com/sun/jna/platform/win32/COM/WbemcliUtil.java:311

            HRESULT hres = null;
            for (T property : propertyEnum.getEnumConstants()) {
                wstrMap.put(property, new WString(property.name()));
            }
            while (enumerator.getPointer() != Pointer.NULL) {
                // Enumerator will be released by calling method so no need to
                // release it here.
                hres = enumerator.Next(timeout, pclsObj.length, pclsObj, uReturn);
                // Enumeration complete or no more data; we're done, exit the loop
                if (hres.intValue() == Wbemcli.WBEM_S_FALSE || hres.intValue() == Wbemcli.WBEM_S_NO_MORE_DATA) {
                    break;
                }
                // Throw exception to notify user of timeout
                if (hres.intValue() == Wbemcli.WBEM_S_TIMEDOUT) {
                    throw new TimeoutException("No results after " + timeout + " ms.");
                }
                // Other exceptions here.
                if (COMUtils.FAILED(hres)) {
                    throw new COMException("Failed to enumerate results.", hres);
                }

                VARIANT.ByReference pVal = new VARIANT.ByReference();
                IntByReference pType = new IntByReference();

                // Get the value of the properties
                IWbemClassObject clsObj = new IWbemClassObject(pclsObj[0]);
                for (T property : propertyEnum.getEnumConstants()) {
                    clsObj.Get(wstrMap.get(property), 0, pVal, pType, null);
                    int vtType = (pVal.getValue() == null ? Variant.VT_NULL : pVal.getVarType()).intValue();
                    int cimType = pType.getValue();
                    switch (vtType) {
                        case Variant.VT_BSTR:
                            values.add(vtType, cimType, property, pVal.stringValue());
                            break;
                        case Variant.VT_I4:
                            values.add(vtType, cimType, property, pVal.intValue());
                            break;

View on GitHub (pinned to d036ad9781)

Solutions

Inspect the HRESULT inside the COMException (getHresult()) and match it against Wbemcli constants to find the specific cause.
Run winmgmt /verifyrepository and rebuild the WMI repository if corrupt.
Check permissions on the WMI namespace (e.g. wmimgmt.msc -> WMI Control -> Security).
Simplify the query and test with wbemtest or PowerShell Get-WmiObject to isolate provider failures.

Example fix

// before
try { result = query.execute(); } catch (COMException e) { throw e; }
// after
try {
    result = query.execute();
} catch (COMException e) {
    log.error("WMI enumerate failed, hresult=0x{}", Integer.toHexString(e.getHresult().intValue()), e);
    throw e;
}

Defensive patterns

Strategy: try-catch

Try / catch

try {
    result = query.execute();
} catch (COMException e) {
    int hres = e.getHresult() != null ? e.getHresult().intValue() : -1;
    switch (hres) {
        case Wbemcli.WBEM_E_ACCESS_DENIED: /* fix namespace permissions */ break;
        case Wbemcli.WBEM_E_INVALID_QUERY: /* fix WQL */ break;
        default: /* repository/provider failure */
    }
}

Prevention

Log the wrapped HRESULT for every COMException
Validate WQL with wbemtest/PowerShell first
Check WMI namespace security for the invoking user

When it happens

Trigger: The WMI enumerator returns a failing HRESULT — e.g. WBEM_E_FAILED, WBEM_E_INVALID_QUERY, WBEM_E_ACCESS_DENIED, or WBEM_E_NOT_SUPPORTED from the underlying provider — during Next().

Common situations: WMI repository corruption; provider-specific failures (e.g. corrupted performance counters for Win32_PerfFormattedData classes); permission problems on remote namespaces; WMI service throttling.

Related errors

AI-assisted analysis of java-native-access/jna@d036ad9781 (2026-09-12). Data as JSON: /api/errors/855efd887c40fde2. Report an issue: GitHub.