Failed to write ${label.toLowerCase()} "${filePath}": ${form

Error message

Failed to write ${label.toLowerCase()} "${filePath}": ${formatErrorForLog(error)}

What it means

Thrown by writeWorkspaceFile in the sandbox-only branch (no workspace.filesystem defined): writeFileViaSandbox failed and it was not an abort error. The original error is attached as `cause`. This path is taken for command-only sandbox providers like Daytona that expose no filesystem API — only shell command execution.

Source

Thrown at packages/@n8n/instance-ai/src/workspace/workspace-files.ts:162

				});
				return;
			} catch (fallbackError) {
				if (isAbortError(fallbackError)) throw fallbackError;
				// Preserve whichever path carries quota metadata so callers can
				// classify the combined failure correctly.
				throw new Error(
					`Failed to write ${label.toLowerCase()} "${filePath}": ${formatErrorForLog(error)}; command fallback failed: ${formatErrorForLog(fallbackError)}`,
					{ cause: selectWriteFailureCause(error, fallbackError) },
				);
			}
		}
	}

	try {
		await writeFileViaSandbox(workspace, filePath, content, options);
	} catch (error) {
		if (isAbortError(error)) throw error;
		throw new Error(
			`Failed to write ${label.toLowerCase()} "${filePath}": ${formatErrorForLog(error)}`,
			{ cause: error },
		);
	}
}

export async function writeWorkspaceFileMap(
	workspace: WorkspaceFileTarget,
	files: Map<string, string>,
	options?: WorkspaceFileOptions,
): Promise<void> {
	await Promise.all(
		Array.from(files, async ([filePath, content]) => {
			await writeWorkspaceFile(workspace, filePath, content, options);
		}),
	);
}

View on GitHub (pinned to 5ac6606e81)

Solutions

Read err.cause for the underlying command stderr — it carries the real reason (permission, disk, decode failure).
If the file is large and E2BIG is suspected, split the content into smaller writes or reduce BASE64_WRITE_CHUNK_SIZE.
Verify the sandbox shell supports base64 -d and printf (the command fallback assumes a POSIX shell).
Check workspace permissions on the target directory.

Example fix

// before
await writeWorkspaceFile(workspace, filePath, content, opts);

// after — surface the underlying command error
try {
  await writeWorkspaceFile(workspace, filePath, content, opts);
} catch (err) {
  const detail = err.cause instanceof Error ? err.cause.message : String(err.cause);
  throw new Error(`Workspace write to ${filePath} failed: ${detail}`);
}

Defensive patterns

Strategy: try-catch

Type guard

function isSandboxWriteError(error: unknown): boolean {
  return error instanceof Error && /Failed to write/.test(error.message);
}

Try / catch

try {
  await writeWorkspaceFile(workspace, filePath, content, opts);
} catch (err) {
  const detail = err.cause instanceof Error ? err.cause.message : String(err.cause);
  logger.error('sandbox write failed', { path: filePath, detail });
  throw err;
}

Prevention

Inspect err.cause for the underlying command stderr to find the real reason.
Confirm the sandbox shell is POSIX (supports base64 -d, printf) before relying on the command path.
For very large files, write in chunks to avoid E2BIG on the base64 printf.

When it happens

Trigger: Calling writeWorkspaceFile where workspace.filesystem is undefined (workspace.sandbox only), and writeFileViaSandbox throws a non-abort error after its own retry loop. This includes non-transient command failures (exit code != 0, base64 decode failure, mkdir failure) that the retry loop does not retry.

Common situations: Sandbox command write exited non-zero because the target path is read-only or permission denied; base64 decode failed because the chunked printf was truncated mid-transfer (E2BIG on a huge file); the workspace ran out of disk mid-write; the sandbox shell is non-POSIX and lacks base64/printf.

Related errors

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/799439aed9a57857. Report an issue: GitHub.