How to Fix Supabase Storage Upload Error in AI-Built Apps
File uploads to Supabase Storage fail silently or throw permission errors. AI-generated upload code often misses bucket policies, file size limits, or correct content type headers.
Error messages you might see
StorageApiError: new row violates row-level security policyError: The resource already exists. Duplicate key violation.Why this happens in AI-generated code
Missing RLS policies on storage
AI creates storage buckets but doesn't add row-level security policies allowing uploads.
File path collisions
AI uses predictable file names that collide when multiple users upload files simultaneously.
Exceeding file size limits
Default Supabase upload limits are hit because AI code doesn't implement client-side validation.
How to fix it
Configure storage RLS policies
Add INSERT policies on `storage.objects` that match your auth requirements: `(bucket_id = 'avatars' AND auth.uid()::text = (storage.foldername(name))[1])`.
Use unique file paths
Include user ID and timestamp in file paths: `${userId}/${Date.now()}-${filename}` to prevent collisions.
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Frequently asked questions
How do I make a Supabase storage bucket public?
Set the bucket to public in Dashboard or via `createBucket('name', { public: true })`. Public buckets still need RLS policies for uploads.
What is the maximum upload size for Supabase?
Default is 50MB per file. You can increase this in your project settings, up to 5GB for Pro plans.
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