diff --git a/src/lib/services/furni-import.ts b/src/lib/services/furni-import.ts
index 04e6590e8c..fa4c78b6f6 100644
--- a/src/lib/services/furni-import.ts
+++ b/src/lib/services/furni-import.ts
@@ -750,7 +750,7 @@ export async function importSingleFurni(params: {
 		!existsSync(/*turbopackIgnore: true*/ nitroPath)
 	) {
 		const nitroUrl = `${sourceNitroBaseUrl}/${encodeURIComponent(safeNitroName)}.nitro`;
-		const dl = await downloadFile(nitroUrl, nitroPath, { validate: "png" });
+		const dl = await downloadFile(nitroUrl, nitroPath, { validate: "nitro" });
 		if (dl.ok) nitroDownloadOk = true;
 	}
 
@@ -843,7 +843,10 @@ export async function importSingleFurni(params: {
 			warnings,
 			error: isUpdate
 				? "No .nitro file could be created; existing furniture was preserved"
-				: "Import rolled back: no .nitro file could be created",
+				: `Import rolled back: no .nitro file could be created. ${warnings
+						.filter((warning) => /conversion|download|SWF/.test(warning))
+						.slice(-3)
+						.join(". ")}`,
 		};
 	}
 
diff --git a/src/lib/services/import/core/download.test.ts b/src/lib/services/import/core/download.test.ts
index 883b00dc02..1d491602d5 100644
--- a/src/lib/services/import/core/download.test.ts
+++ b/src/lib/services/import/core/download.test.ts
@@ -1,5 +1,10 @@
 import { describe, expect, it } from "vitest";
-import { validatePngBytes, validateSwfBytes } from "./download";
+import { createNitroBundle } from "../../swf/nitro-builder";
+import {
+	validateNitroBytes,
+	validatePngBytes,
+	validateSwfBytes,
+} from "./download";
 
 describe("import/core/download validators", () => {
 	it("accepts FWS/CWS/ZWS swf magic", () => {
@@ -22,3 +27,14 @@ describe("import/core/download validators", () => {
 		expect(validatePngBytes(Buffer.from([1, 2, 3, 4, 5, 6, 7, 8]))).toBe(false);
 	});
 });
+
+it("validates nitro bundles separately from PNG files", () => {
+	const png = Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]);
+	const bundle = createNitroBundle({ name: "chair" }, png, "chair");
+	expect(validateNitroBytes(bundle)).toBe(true);
+	expect(validatePngBytes(bundle)).toBe(false);
+	expect(validateNitroBytes(png)).toBe(false);
+	expect(validateNitroBytes(Buffer.from("<html>Access denied</html>"))).toBe(
+		false,
+	);
+});
diff --git a/src/lib/services/import/core/download.ts b/src/lib/services/import/core/download.ts
index 603af91775..669e5542b5 100644
--- a/src/lib/services/import/core/download.ts
+++ b/src/lib/services/import/core/download.ts
@@ -1,4 +1,5 @@
 import { promises as fs } from "node:fs";
+import { parseNitroBundle } from "../../swf/nitro-builder";
 
 import { browserHeaders } from "./browser-headers";
 
@@ -18,6 +19,20 @@ export function validatePngBytes(buffer: Buffer): boolean {
 	);
 }
 
+export function validateNitroBytes(buffer: Buffer): boolean {
+	try {
+		const bundle = parseNitroBundle(buffer);
+		return (
+			!!bundle.json &&
+			typeof bundle.json === "object" &&
+			!Array.isArray(bundle.json) &&
+			validatePngBytes(bundle.png)
+		);
+	} catch {
+		return false;
+	}
+}
+
 export async function tryDownloadCandidates(
 	urls: string[],
 	destPath: string,
@@ -33,7 +48,7 @@ export async function tryDownloadCandidates(
 export async function downloadFile(
 	url: string,
 	destPath: string,
-	options?: { maxRetries?: number; validate?: "swf" | "png" },
+	options?: { maxRetries?: number; validate?: "swf" | "png" | "nitro" },
 ): Promise<{ ok: boolean; size: number }> {
 	const maxRetries = options?.maxRetries ?? 3;
 	const baseDelay = 1000;
@@ -79,6 +94,8 @@ export async function downloadFile(
 				}
 				continue;
 			}
+			if (options?.validate === "nitro" && !validateNitroBytes(buffer))
+				return { ok: false, size: 0 };
 			await fs.writeFile(/*turbopackIgnore: true*/ destPath, buffer);
 			return { ok: true, size: buffer.length };
 		} catch (err) {
diff --git a/src/lib/services/swf/conversion-pool-recovery.test.ts b/src/lib/services/swf/conversion-pool-recovery.test.ts
new file mode 100644
index 0000000000..c261a7479c
--- /dev/null
+++ b/src/lib/services/swf/conversion-pool-recovery.test.ts
@@ -0,0 +1,45 @@
+// @vitest-environment node
+import { EventEmitter } from "node:events";
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const mocks = vi.hoisted(() => ({
+	convert: vi.fn(() => ({ bundle: Buffer.from("converted") })),
+	icon: vi.fn(() => Buffer.from("icon")),
+}));
+vi.mock("./index", () => ({
+	convertSwfToNitro: mocks.convert,
+	extractIconFromSwf: mocks.icon,
+}));
+vi.mock("node:worker_threads", () => ({
+	Worker: class extends EventEmitter {
+		postMessage() {
+			queueMicrotask(() =>
+				this.emit("error", new Error("worker module missing")),
+			);
+		}
+	},
+}));
+afterEach(() => {
+	vi.unstubAllEnvs();
+	vi.resetModules();
+	vi.clearAllMocks();
+});
+describe("conversion worker recovery", () => {
+	it("falls back when worker startup rejects the conversion job", async () => {
+		vi.stubEnv("NODE_ENV", "production");
+		vi.stubEnv("VITEST", undefined);
+		const { convertSwfToNitroAsync } = await import("./conversion-pool");
+		const data = Buffer.from("SWF");
+		const result = await convertSwfToNitroAsync(data, "chair");
+		expect(result.bundle.toString()).toBe("converted");
+		expect(mocks.convert).toHaveBeenCalledWith(data, "chair");
+	});
+	it("recovers icon extraction from a worker startup error", async () => {
+		vi.stubEnv("NODE_ENV", "production");
+		vi.stubEnv("VITEST", undefined);
+		const { extractIconFromSwfAsync } = await import("./conversion-pool");
+		expect(
+			(await extractIconFromSwfAsync(Buffer.from("SWF"), "chair"))?.toString(),
+		).toBe("icon");
+	});
+});
diff --git a/src/lib/services/swf/conversion-pool.ts b/src/lib/services/swf/conversion-pool.ts
index 58821516e6..3e217fd463 100644
--- a/src/lib/services/swf/conversion-pool.ts
+++ b/src/lib/services/swf/conversion-pool.ts
@@ -154,8 +154,10 @@ export async function convertSwfToNitroAsync(
 	buffer: Buffer,
 	classname: string,
 ): Promise<ConversionResult> {
-	const res = await run({ type: "convert", buffer, classname });
-	if (res.ok && res.result) return res.result;
+	const res = await run({ type: "convert", buffer, classname }).catch(
+		() => null,
+	);
+	if (res?.ok && res.result) return res.result;
 	// Worker failed for this item — fall back to the main thread.
 	return convertSwfToNitro(buffer, classname);
 }
@@ -164,7 +166,7 @@ export async function extractIconFromSwfAsync(
 	buffer: Buffer,
 	classname: string,
 ): Promise<Buffer | null> {
-	const res = await run({ type: "icon", buffer, classname });
-	if (res.ok) return res.icon ?? null;
+	const res = await run({ type: "icon", buffer, classname }).catch(() => null);
+	if (res?.ok) return res.icon ?? null;
 	return extractIconFromSwf(buffer, classname);
 }