Cursor·FixdatabaseSupabasebeginner

Cursor Supabase Storage Upload Failing

Quick Answer

The bucket policy, file path, or upload call generated by Cursor does not match the actual Supabase Storage setup. In many cases, the bucket is private with no matching INSERT policy, or the public URL is being built incorrectly. Start with "Check the bucket name and Storage policies" before making broader code changes.

You're in the right place if...

!File picker works but the upload fails
!Supabase bucket stays empty after upload
!Images upload locally but fail on the deployed app

Why this happens

Fix

Check the bucket name and Storage policies

In Supabase Storage, verify the bucket exists, the path is correct, and the app has permission to insert objects into that bucket.

Create the right policy for uploads

If authenticated users upload their own files, start with a policy like this and then tighten it later.

create policy "Allow authenticated uploads"
on storage.objects
for insert
to authenticated
with check (bucket_id = 'uploads');

create policy "Allow reads"
on storage.objects
for select
using (bucket_id = 'uploads');

Regenerate the upload flow in Cursor

Make Cursor use the exact bucket and public URL strategy you want.

Copy this prompt

Supabase Storage uploads are failing.
Please update the upload flow to:
1. use the correct bucket name
2. upload with the right authenticated or anonymous context
3. return a valid public URL or signed URL
4. show a clear error message if the upload fails

Prevent this next time

Decide whether the bucket is public or private before wiring uploads. Most broken upload flows come from changing that decision mid-build.