Failed to load plugin resource as stream {} with classLoader

Error message

Failed to load plugin resource as stream {} with classLoader

What it means

BootstrapClassLoaderHandler.getResourceAsStream tries to return the bytecode stream of a plugin class resource from the bootstrap classloader. If appendToBootstrapClassLoaderSearch or getResourceAsStream throws, the handler logs this warn and returns null instead of propagating. A null result means callers (e.g. bytecode reading) cannot obtain the plugin class resource.

Source

Thrown at agent-module/profiler/src/main/java/com/navercorp/pinpoint/profiler/instrument/classloading/BootstrapClassLoaderHandler.java:93

                // Reordering is not recommended.
                this.injectedToRoot = true;
            }
        }
    }

    @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;
    }
}

View on GitHub (pinned to 744c3d3075)

Solutions

Inspect the exception stack trace attached to this warn for the root cause.
Verify the plugin jar is appended to the bootstrap classloader search before resource lookup.
Check the internalName ends with .class and matches the packaged resource path.
Ensure callers handle a null InputStream return value.

Example fix

// before
InputStream in = injector.getResourceAsStream(cl, internalName);
byte[] bytes = IOUtils.toByteArray(in); // NPE if null
// after
InputStream in = injector.getResourceAsStream(cl, internalName);
if (in == null) {
    logger.warn("plugin resource {} unavailable", internalName);
    return null;
}

Defensive patterns

Strategy: fallback

Validate before calling

if (targetClassLoader != Object.class.getClassLoader()) { throw new IllegalArgumentException("not bootstrap loader"); }

Try / catch

InputStream in = handler.getResourceAsStream(cl, internalName);
if (in == null) { log.warn("no bytecode stream for {}", internalName); return null; }

Prevention

Null-check the returned stream before use
Ensure appendToBootstrapClassLoaderSearch succeeded before lookup
Use correct internalName format (path/Foo.class)
Watch for security-manager denials in the log

When it happens

Trigger: Any Exception (I/O, security, ClassCastException on the loader, etc.) thrown while appending to bootstrap search or fetching internalName as a stream from the bootstrap classloader.

Common situations: Plugin jar not on the bootstrap path; resource name (internal name with .class) mistyped; security manager denying classloader access; plugin jar unreadable.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

AI-assisted analysis of pinpoint-apm/pinpoint@744c3d3075 (2026-09-07). Data as JSON: /api/errors/237740fdb3c6be22. Report an issue: GitHub.