What causes "Unexpected error: %d\n" in openjdk/jdk?

Decode the number against the jvmtiError enum (e.g. 30=WRONG_PHASE, 109=OUT_OF_MEMORY) and address that condition

Unexpected error: %d\n

Error message

Unexpected error: %d\n

What it means

Generic reason suffix for the bootstrap-add warning: AddToBootstrapClassLoaderSearch returned an unexpected JVMTI error code (number printed). Typical codes: 30 WRONG_PHASE (JVM past live phase), 109 OUT_OF_MEMORY, or internal errors. The entry is skipped and startup continues.

Source

Thrown at src/java.instrument/share/native/libinstrument/InvocationAdapter.c:970

                haveBasePath = 1;
            }

            resolved = resolve(parent, path);
            jvmtierr = (*jvmtienv)->AddToBootstrapClassLoaderSearch(jvmtienv, resolved);
            free(resolved);
        }

        /* print warning if boot class path not updated */
        if (jvmtierr != JVMTI_ERROR_NONE) {
            check_phase_blob_ret(jvmtierr, free(path));

            fprintf(stderr, "WARNING: %s not added to bootstrap class loader search: ", path);
            switch (jvmtierr) {
                case JVMTI_ERROR_ILLEGAL_ARGUMENT :
                    fprintf(stderr, "Illegal argument or not JAR file\n");
                    break;
                default:
                    fprintf(stderr, "Unexpected error: %d\n", jvmtierr);
            }
        }

        /* finished with the path */
        free(path);
    }


    /* clean-up */
    if (haveBasePath && parent != canonicalPath) {
        free(parent);
    }
    free(paths);
}

View on GitHub (pinned to 88dfb74bbe)

Solutions

Decode the number against the jvmtiError enum (e.g. 30=WRONG_PHASE, 109=OUT_OF_MEMORY) and address that condition
Load the agent earlier (launch-time -javaagent) so boot path updates happen in the correct phase
Free native memory / raise limits if OOM is indicated
Retry the load once the JVM is stably in the live phase

Example fix

# before: attaching during shutdown
vm.loadAgent(...); // WRONG_PHASE (30)
# after: attach while app is running
vm.loadAgent(...);

Defensive patterns

Strategy: fallback

Validate before calling

// check JVM liveness phase before attaching
if (vm instanceof VirtualMachine && Boolean.getBoolean("shutdown.in.progress"))
    throw new IllegalStateException("refusing to attach during shutdown");

Prevention

Attach during stable live phase; avoid shutdown hooks
Decode unexpected JVMTI codes against the jvmtiError enum before retrying blindly

When it happens

Trigger: Boot-Class-Path processing occurring during JVM shutdown/wrong phase; native OOM; JVMTI internal failure.

Common situations: Agents attaching late in JVM lifetime; memory-pressured JVMs; rarely, JDK bugs.

Related errors

AI-assisted analysis of openjdk/jdk@88dfb74bbe (2026-08-14). Data as JSON: /api/errors/fecfe643fe1efebe. Report an issue: GitHub.