Product review widget not loading — CORS 503 Error

Question

Hi, I recently installed Klaviyo Reviews on my Shopify store (nativva.com) and the review widgets are not loading correctly in any browser (Chrome or Safari).

The error appearing in the browser console is:

"Fetch API cannot load https://fast.a.klaviyo.com/reviews/api/client_onsite_widgets?company_id=WJgbKv due to access control checks. Origin https://www.nativva.com is not allowed by Access-Control-Allow-Origin. Status code: 503"

Behavior: All Klaviyo Reviews widgets work randomly and inconsistently — sometimes they display and sometimes they don't, without any changes to our configuration. This affects:

Star Rating on product pages
Full review block on product pages
Featured Reviews Carousel on the homepage

The issue occurs on both Chrome and Safari, in both normal and incognito mode.

ArpitBanjara · Answer

hey ​@NATIVVAI think that's a "server unavailable" response coming from Klaviyo'sendpoint, and when the server can't respond properly, it also fails to send back the CORS headers the browser expects.I would suggest checkingstatus.klaviyo.com and look for any recent incidents related to the Reviews API or their CDN.Klaviyo has had some API instability recently, so it's worth ruling that out. I would also suggest that you verifyhe company_id in the widget URL still matches your public API key, and that the Reviews app is still properly connected in your Shopify admin.If all of that looks fine, I think the best next step is reaching out to Klaviyo Support directly with the console error and the failing URL. They'd be able to tell you more than I can from here since I can't see your account. I will cc ​@Byrne C​@GabbyEspositoso that they can take this forward from here.I hope this helps,cheersArpit

Sign up

Use your Klaviyo credentials

Log in to the Community

Use your Klaviyo credentials

Scanning file for viruses.

This file cannot be downloaded