pinpoint-apm/pinpoint · warning

Invalid bootstrap class loader. cl=

Error message

Invalid bootstrap class loader. cl={}

What it means

This warn is the fallback path of BootstrapClassLoaderHandler.getResourceAsStream: the provided targetClassLoader is not the bootstrap classloader, so the handler refuses to look up the resource and returns null. It signals an API misuse — a bootstrap-classloader-only handler was given a non-bootstrap loader.

Solutions

1. Verify targetClassLoader is actually the bootstrap loader before calling this handler.
2. Route non-bootstrap loaders to PlainClassLoaderHandler (or URLClassLoaderHandler) in PluginClassInjector.
3. Log/handle the null return instead of assuming a valid stream.
4. Check for containers that wrap the bootstrap loader in a delegating wrapper and compare against Object.class.getClassLoader() semantics.

Example fix

// before
handler.getResourceAsStream(targetClassLoader, internalName);
// after
if (targetClassLoader == Object.class.getClassLoader()) {
    return bootstrapHandler.getResourceAsStream(targetClassLoader, internalName);
}
return plainHandler.getResourceAsStream(targetClassLoader, internalName);

boolean isBootstrap = (targetClassLoader == Object.class.getClassLoader());

static boolean isBootstrapClassLoader(ClassLoader cl) {
    return cl == Object.class.getClassLoader();
}

When it happens

Trigger: getResourceAsStream invoked with any ClassLoader other than the bootstrap loader (PluginClassInjector only routes here when the target loader is the bootstrap loader, so a routing/mismatch or custom call with the wrong loader triggers it).

Common situations: Custom instrumentation code calling the bootstrap handler directly with an application classloader; changes in loader routing logic; classloader identity assumptions broken by custom containers.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• duplicated pluginClass
• Failed to load plugin class
• Failed to load plugin class
• Failed to load plugin class
• Failed to load plugin class

AI-assisted analysis of pinpoint-apm/pinpoint@744c3d3075 (2026-09-07). Data as JSON: /api/errors/6ea09f8e6e2962fa. Report an issue: GitHub.

Appendix: source

Thrown at agent-module/profiler/src/main/java/com/navercorp/pinpoint/profiler/instrument/classloading/BootstrapClassLoaderHandler.java:96

        }
    }

    @Override
    public InputStream getResourceAsStream(ClassLoader targetClassLoader, String internalName) {
        try {
            if (targetClassLoader == null) {
                ClassLoader classLoader = ClassLoader.getSystemClassLoader();
                if (classLoader == null) {
                    return null;
                }
                appendToBootstrapClassLoaderSearch();
                return classLoader.getResourceAsStream(internalName);
            }
        } catch (Exception e) {
            logger.warn("Failed to load plugin resource as stream {} with classLoader", internalName, e);
            return null;
        }
        logger.warn("Invalid bootstrap class loader. cl={}", targetClassLoader);
        return null;
    }
}

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