openjdk/jdk · error · NullPointerException

Failed to retrieve atom name.

Error message

Failed to retrieve atom name.

What it means

XlibWrapper.XGetAtomName called XGetAtomName() and got NULL back — the X server does not know an atom with that numeric ID. The code prints 'Atom was <n>' to stderr and throws java.lang.NullPointerException('Failed to retrieve atom name.') to Java. Atoms exist only while the server keeps them; an unknown ID means the atom was never interned on this display or was created on a different server.

Source

Thrown at src/java.desktop/unix/native/libawt_xawt/xawt/XlibWrapper.c:1698

}

/*
 * Class:     sun_awt_X11_XlibWrapper
 * Method:    XGetAtomName
 * Signature: (JJ)Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL
Java_sun_awt_X11_XlibWrapper_XGetAtomName(JNIEnv *env, jclass clazz,
                      jlong display, jlong atom)
{
    jstring string = NULL;
    char* name;
    AWT_CHECK_HAVE_LOCK_RETURN(NULL);
    name = (char*) XGetAtomName((Display*)jlong_to_ptr(display), atom);

    if (name == NULL) {
        fprintf(stderr, "Atom was %d\n", (int)atom);
        JNU_ThrowNullPointerException(env, "Failed to retrieve atom name.");
        return NULL;
    }

    string = (*env)->NewStringUTF(env, (const char *)name);

    XFree(name);

    return string;
}

/*
 * Class:     sun_awt_X11_XlibWrapper
 * Method:    XMaxRequestSize
 * Signature: (J)J
 */
JNIEXPORT jlong JNICALL
Java_sun_awt_X11_XlibWrapper_XMaxRequestSize(JNIEnv *env, jclass clazz,
                         jlong display) {

View on GitHub (pinned to 88dfb74bbe)

Solutions

1. Do not cache atom IDs across connections: re-intern with XInternAtom (XAtom.get()/XlibWrapper.XInternAtom) per display/session
2. Validate the atom ID is nonzero and came from the same Display connection before calling XGetAtomName
3. Catch the NullPointerException at the call site and degrade gracefully (treat property/atom as absent)
4. Check for a stale DISPLAY / reconnected SSH X11 forwarding and restart the app against the current server

Example fix

// before
String name = XlibWrapper.XGetAtomName(display, atom); // may NPE if atom unknown

// after
String name = null;
try {
    name = XlibWrapper.XGetAtomName(display, atom);
} catch (NullPointerException e) {
    // atom not interned on this display — recover
}

// intern the name instead of trusting a cached numeric atom id
long atom = XlibWrapper.XInternAtom(display, "_MY_PROPERTY", false); // creates-or-finds, never unknown

String name;
try {
    name = XlibWrapper.XGetAtomName(display, atom);
} catch (NullPointerException npe) {
    name = null; // atom not interned on this display — treat as absent
}

When it happens

Trigger: Java_sun_awt_X11_XlibWrapper_XGetAtomName being invoked with an atom value that came from a stale/closed display, was read from a property of another client that has exited (its atoms may be unregistered), or is simply garbage (uninitialized long). Xlib APIs like XGetAtomName return NULL for never-interned IDs.

Common situations: Debugging tools that cache atom IDs across display reconnects (X restart, ssh -X reconnection); window-manager interactions where the WM exited and its private atoms vanished; passing XA_* predefined values works, but custom names misspelled when interning earlier. The NPE surfaces in X11-based AWT internals or XlibWrapper users.

Related errors

• Couldn't find X Input Context\n
• Couldn't find X Input Context
• %s\n
• java.lang.instrument/-javaagent: unknown error\n
• Error: Out of memory in ADLC\n

AI-assisted analysis of openjdk/jdk@88dfb74bbe (2026-08-14). Data as JSON: /api/errors/424b4717dbf26a74. Report an issue: GitHub.