diff --git a/src/app/api/v1/finance/costing/validate/bulk_product_routing/route.ts b/src/app/api/v1/finance/costing/validate/bulk_product_routing/route.ts
index a52dbd8..698a289 100644
--- a/src/app/api/v1/finance/costing/validate/bulk_product_routing/route.ts
+++ b/src/app/api/v1/finance/costing/validate/bulk_product_routing/route.ts
@@ -23,6 +23,12 @@ export async function POST(request: NextRequest) {
       metadata,
     )
 
+    // Surface backend errors (e.g. timeout on very large files) as a non-2xx response
+    // so the frontend can display the message rather than showing an empty result.
+    if (res.base && !res.base.isSuccess) {
+      return NextResponse.json({ base: res.base }, { status: 422 })
+    }
+
     return NextResponse.json({
       isValid: res.isValid,
       sheets: res.sheets.map((sheet) => ({
diff --git a/src/services/finance/cost-import-api.ts b/src/services/finance/cost-import-api.ts
index 37c0083..2ecd952 100644
--- a/src/services/finance/cost-import-api.ts
+++ b/src/services/finance/cost-import-api.ts
@@ -227,7 +227,10 @@ export async function validateBulkProductRoutingFile(
     headers: { "Content-Type": "application/json" },
     body: JSON.stringify({ fileContent, fileName: file.name }),
   })
-  if (!res.ok) throw new Error(`Validation failed: ${res.status}`)
+  if (!res.ok) {
+    const errJson = await res.json().catch(() => null)
+    throw new Error(errJson?.base?.message || `Validation failed: ${res.status}`)
+  }
   const json = await res.json()
 
   if (!json.base?.isSuccess && json.base?.isSuccess !== undefined) {