name: supabase-silent-insert-uuid-debug

description: Debug silent INSERT failures in Supabase — UUID default collision causing silent failures

triggers:

- insert not working no error

- cargo não salva

- duplicate key on id column

- uuid default fixed value

Supabase Silent INSERT Failure — UUID Default Collision

Problem

INSERT appears to silently fail in Supabase admin panel. No error shown to user, data doesn't save. Code looks correct, RLS policies look fine.

Root Cause

A column (usually id) has a fixed default UUID instead of uuid_generate_v4(). Every INSERT tries to use the same UUID, violating a UNIQUE or PRIMARY KEY constraint. The error is swallowed by the frontend's error handling.

Symptoms

• - INSERT via Supabase JS returns { data: null, error: null } or silently fails
• - Direct SQL INSERT gives: duplicate key value violates unique constraint
• - SELECT works fine, UPDATE might work
• - The table has 1-2 rows with IDs like 00000000-0000-0000-0000-000000000001

Debug Steps

1. Check current UUID defaults

`sql

SELECT column_default FROM information_schema.columns

WHERE table_name = 'your_table' AND column_name = 'id';

`

2. Check existing rows' IDs

`sql

SELECT id FROM your_table ORDER BY created_at;

`

If IDs look like 00000000-... instead of random UUIDs → bad default.

3. Test INSERT directly on DB

`sql

INSERT INTO your_table (name, description) VALUES ('Test', 'desc') RETURNING id;

`

4. Check for constraint violations

`sql

SELECT conname, pg_get_constraintdef(oid)

FROM pg_constraint WHERE conrelid = 'your_table'::regclass;

`

Fix

`sql

-- Remove fixed default

ALTER TABLE your_table ALTER COLUMN id DROP DEFAULT;

-- Add proper UUID generation

ALTER TABLE your_table ALTER COLUMN id SET DEFAULT uuid_generate_v4();

`

Verify fix works:

`sql

INSERT INTO your_table (name) VALUES ('TestFix') RETURNING id;

-- Should return a random UUID like: 97cc404c-a9a3-4107-944b-e919a5564ecf

`

Prevention

When creating tables in Supabase, always use gen_random_uuid() or uuid_generate_v4() as the id column default — not hardcoded UUIDs.

When RLS is NOT the issue

• - RLS policies are PERMISSIVE with public role → should allow all
• - SELECT works but INSERT fails silently
• - Error doesn't surface in browser console