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.

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.

Appendix: 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)