Invalid execArgv passed to Worker constructor
Production Risk
Low — caught at startup; review which flags are valid in worker context.
Thrown when the execArgv option passed to new Worker() contains flags that are not allowed in a worker context, or flags that require a value but are missing one. Some Node.js CLI flags cannot be used inside worker threads.
- 1Passing --prof or --prof-process in worker execArgv (not allowed in workers)
- 2Passing an incomplete flag that requires an argument
- 3Including flags that require process-level changes not applicable to workers
Triggered when the Worker constructor validates the execArgv option.
const { Worker } = require('worker_threads');
new Worker('./w.js', {
execArgv: ['--prof'], // profiling flags not allowed in workers
});expected output
Error [ERR_WORKER_INVALID_EXEC_ARGV]: Initiated Worker with invalid execArgv flags: --prof
Fix 1
Use only allowed flags in worker execArgv
WHEN When customising the worker Node.js runtime
const w = new Worker('./w.js', {
execArgv: ['--max-old-space-size=512', '--harmony'],
});Why this works
Only standard V8/Node.js flags that are valid in a forked context are permitted in worker execArgv.
Fix 2
Profile at the main process level instead
WHEN When you need CPU profiling
// Run the main process with --prof and let workers be created normally // node --prof main.js
Why this works
Process-level profiling flags apply to the entire V8 instance; workers share the profiler.
const { Worker } = require('worker_threads');
new Worker('./w.js', {
execArgv: ['--prof'], // profiling flags not allowed in workers
}); // this triggers ERR_WORKER_INVALID_EXEC_ARGVtry {
// operation that may throw ERR_WORKER_INVALID_EXEC_ARGV
riskyOperation()
} catch (err) {
if (err.code === 'ERR_WORKER_INVALID_EXEC_ARGV') {
console.error('ERR_WORKER_INVALID_EXEC_ARGV:', err.message)
} else {
throw err
}
}// Validate inputs before calling the operation
function safe_err_worker_invalid_exec_argv(...args) {
// validate args here
return performOperation(...args)
}✕ Copy all main process execArgv into worker execArgv
Some flags are only valid at process start and cannot be applied to individual worker threads.
Node.js Error Codes Documentation
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