diff --git a/js/script.js b/js/script.js
index 8dc3d31..4b1d1e7 100644
--- a/js/script.js
+++ b/js/script.js
@@ -79,6 +79,17 @@ function toLatinDigits(str) {
   });
 }
 
+function getApiErrorMessage(body, fallback) {
+  const detailsMessage = body?.details?.message;
+  if (typeof detailsMessage === "string" && detailsMessage.trim()) {
+    return detailsMessage.trim();
+  }
+  if (typeof body?.status_message === "string" && body.status_message.trim()) {
+    return body.status_message.trim();
+  }
+  return fallback;
+}
+
 // Normalizes Iranian mobile numbers (09xxxxxxxxx, 9xxxxxxxxx, 0098/98/+98 prefixed) to E.164.
 function toE164(raw) {
   let cleaned = toLatinDigits(raw.trim()).replace(/[\s-]/g, "");
@@ -98,6 +109,7 @@ async function submitInviteRequest(inviteCode, mobileNumber, token) {
     headers: {
       "Content-Type": "application/json",
       Authorization: `Bearer ${token}`,
+      "Accept-Language": "fa",
     },
     body: JSON.stringify({
       invite_code: inviteCode,
@@ -112,7 +124,9 @@ async function submitInviteRequest(inviteCode, mobileNumber, token) {
     } catch (_) {
       // no JSON body
     }
-    const error = new Error(body?.status_message || `Invite request failed (${response.status})`);
+    const error = new Error(
+      getApiErrorMessage(body, `Invite request failed (${response.status})`)
+    );
     error.status = response.status;
     error.body = body;
     throw error;