FlowiseAI/Flowise · error · Error

${execution.error.name}: ${execution.error.value}

Error message

${execution.error.name}: ${execution.error.value}

What it means

Thrown by the Daytona-based sandbox branch of executeJavascript after sbx.runCode returns an execution with a populated execution.error object. The error carries a name and value from the sandboxed runtime — typically a thrown JS error or a compile-time exception inside the user-supplied code string.

Source

Thrown at packages/components/src/utils.ts:1712

            // Separate imports from the rest of the code for proper ES6 module structure
            const codeWithImports = [
                ...importLines,
                `module.exports = async function() {`,
                ...variableDeclarations,
                ...otherLines,
                `}()`
            ].join('\n')

            const execution = await sbx.runCode(codeWithImports, { language: 'js' })

            let output = ''

            if (execution.text) output = execution.text
            if (!execution.text && execution.logs.stdout.length) output = execution.logs.stdout.join('\n')

            if (execution.error) {
                throw new Error(`${execution.error.name}: ${execution.error.value}`)
            }

            if (execution.logs.stderr.length) {
                throw new Error(execution.logs.stderr.join('\n'))
            }

            // Stream output if streaming function provided
            if (streamOutput && output) {
                streamOutput(output)
            }

            // Clean up sandbox
            sbx.kill()

            return parseOutput(output)
        } catch (e) {
            throw new Error(`Sandbox Execution Error: ${e}`)
        }

View on GitHub (pinned to abe4a8601a)

Solutions

  1. Read execution.error.name + value to identify the exact JS error (e.g. ReferenceError: foo is not defined).
  2. Test the custom function code in isolation (node REPL or a unit test) with the same input variables.
  3. Confirm all imported modules are in the allow-list and installed by the sandbox (librariesToInstall).
  4. Check that flow variables passed into the sandbox match what the code expects.

Example fix

// before
if (execution.error) {
  throw new Error(`${execution.error.name}: ${execution.error.value}`)
}

// after — include line/script context to speed debugging
if (execution.error) {
  throw new Error(`Sandbox code error — ${execution.error.name}: ${execution.error.value}`, )
}
// caller-side: wrap executeJavascript and prepend the offending code excerpt from the node config
Defensive patterns

Strategy: try-catch

Validate before calling

function codeReferencesDefinedVars(code: string, sandboxKeys: string[]): string[] {
  const missing: string[] = []
  for (const k of sandboxKeys) if (!new RegExp(`\\b${k}\\b`).test(code)) missing.push(k)
  return missing
}

Type guard

function isExecutionError(exec: any): exec is { error: { name: string; value: string } } {
  return exec && typeof exec === 'object' && exec.error && typeof exec.error.name === 'string'
}

Try / catch

if (execution.error) {
  const e = new Error(`${execution.error.name}: ${execution.error.value}`)
  ;(e as any).sandboxError = execution.error
  throw e
}

Prevention

When it happens

Trigger: User code in the tool/custom-function node throws a runtime Error (ReferenceError, TypeError, SyntaxError); a referenced variable is undefined; imported module API used incorrectly; code throws because the sandbox lacks an expected env var or file.

Common situations: Building a Custom Tool function with a bug; referencing a flow variable that doesn't exist; calling a dependency's API with the wrong signature inside the sandbox; SyntaxError from malformed user code that survived the import-stripping preprocessor.

Related errors

AI-assisted analysis of FlowiseAI/Flowise@abe4a8601a (2026-08-12). Data as JSON: /api/errors/0cb2970f2afc7403. Report an issue: GitHub.