Failed to fetch errors
Hi there!
I’m running a Next.js app on Vercel using @supabase/ssr for authentication. We’ve registered 40+ users without any issues, but one registrant consistently gets a failed to fetch error when trying to log in — even in Incognito mode.
Details:
• Supabase Auth → Site URL: https://reg.iepa.com
• Additional Redirect URLs include https://reg.iepa.com/**, our Vercel prod URL, localhost dev, and preview URLs.
• CSP temporarily allows connect-src *; to rule out content security issues.
• I can log in to their account on multiple browsers (Chrome, Safari) without issue.
• This appears specific to their device/network, but I’d like to make the login as bulletproof as possible for all users.
• Vercel logs show Insert failed when trying to log error details to a client_errors table — possibly RLS or policy-related.
Questions:
1. Any common causes for failed to fetch in Supabase Auth when the majority of users are unaffected?
2. Could this be due to cookie domain or SameSite settings with @supabase/ssr?
3. Any best practices for handling “one-off” network/corporate firewall issues with Supabase Auth?
4. For the error logging failure — if using an API route to insert into Supabase from Vercel, should I always use the service role key to bypass RLS?
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1 Reply
If it is an RLS or Auth error you would see that in your API Gateway logs.
Do you know if the request is even getting to your instance in those log?
I believe you can search on user id (unless that is just an upcoming feature I saw).