xpipe-io/xpipe · error · BeaconClientException

Unsupported mode: " + msg.getMode().getDisplayName() + ". Su

Error message

Unsupported mode: " + msg.getMode().getDisplayName() + ". Supported: " + String.join(", ", supportedModeIds)

What it means

The daemon's mode-switch endpoint received a DaemonMode whose target AppOperationMode is not supported in this environment. XPipe builds modes conditionally (e.g. headless vs desktop variants), so a mode id that exists on one installation may not be available or startable on another. The error lists all currently supported mode ids to guide the client.

Source

Thrown at app/src/main/java/io/xpipe/app/beacon/api/DaemonModeExchange.java:25

import com.sun.net.httpserver.HttpExchange;
import lombok.Builder;
import lombok.NonNull;
import lombok.Value;
import lombok.extern.jackson.Jacksonized;

public class DaemonModeExchange extends BeaconInterface<DaemonModeExchange.Request> {

    @Override
    public String getPath() {
        return "/daemon/mode";
    }

    @Override
    public Object handle(HttpExchange exchange, Request msg) throws BeaconClientException {
        var mode = AppOperationMode.map(msg.getMode());
        if (!mode.isSupported()) {
            throw new BeaconClientException("Unsupported mode: " + msg.getMode().getDisplayName()
                    + ". Supported: "
                    + String.join(
                            ", ",
                            AppOperationMode.getAll().stream()
                                    .filter(AppOperationMode::isSupported)
                                    .map(AppOperationMode::getId)
                                    .toList()));
        }

        AppOperationMode.switchToSyncIfPossible(mode);
        return Response.builder().usedMode(msg.getMode()).build();
    }

    @Override
    public boolean requiresEnabledApi() {
        return false;
    }

View on GitHub (pinned to d85ca821ba)

Solutions

  1. Read the 'Supported: ...' list from the error and only request one of those mode ids
  2. Install the XPipe variant that includes the desired operation mode (e.g. full desktop package instead of headless)
  3. Update the client library so its DaemonMode enum matches the daemon's supported modes
  4. Skip the mode-switch call on headless systems and keep the default mode

Example fix

// before
client.setMode(DaemonMode.GUI);
// after
if (supportedModes.contains("gui")) {
    client.setMode(DaemonMode.GUI);
} else {
    logger.warn("GUI mode unsupported on this daemon; staying in " + currentMode);
}
Defensive patterns

Strategy: validation

Validate before calling

Set<String> supported = fetchSupportedModes();
if (!supported.contains(requestedMode.getId())) {
    throw new IllegalArgumentException("Mode " + requestedMode + " unsupported; supported: " + supported);
}

Try / catch

try {
    client.setMode(mode);
} catch (BeaconClientException e) {
    if (e.getMessage().startsWith("Unsupported mode")) {
        logger.warn("Falling back to current mode: " + e.getMessage());
    } else throw e;
}

Prevention

When it happens

Trigger: Posting to DaemonModeExchange with msg.getMode() mapping to an AppOperationMode whose isSupported() is false — e.g. requesting 'desktop' mode on a headless server build, or a build lacking a specific operation-mode module.

Common situations: Switching the daemon to background/desktop mode from a client on a machine whose XPipe package was compiled without that mode; CI/headless containers receiving the same requests used on desktop machines; stale clients sending mode ids removed in a newer daemon.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of xpipe-io/xpipe@d85ca821ba (2026-09-06). Data as JSON: /api/errors/540526fd3ff8e0e7. Report an issue: GitHub.