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Database & ORM · Developer Error Resolution Lab

Fix Supabase Error: 'new row violates row-level security policy for table' (Code 42501)

Resolve PostgreSQL and Supabase Row-Level Security (RLS) INSERT/UPDATE permission errors with proper auth.uid() policies.

Triggered Error Message:

PostgrestError: new row violates row-level security policy for table "profiles" (code: "42501")

Customize Solution for Your Environment
-- Run in Supabase SQL Editor:
ALTER TABLE public.profiles ENABLE ROW LEVEL SECURITY;

CREATE POLICY "Allow authenticated insert own rows on profiles"
ON public.profiles
FOR INSERT
TO authenticated
WITH CHECK ((select auth.uid()) = user_id);

CREATE POLICY "Allow authenticated update own rows on profiles"
ON public.profiles
FOR UPDATE
TO authenticated
USING ((select auth.uid()) = user_id)
WITH CHECK ((select auth.uid()) = user_id);

Root Cause & Mechanism Analysis

Why does this error occur?

Row-Level Security (RLS) is enabled on the PostgreSQL table, which denies all writes by default unless an explicit `FOR INSERT WITH CHECK (...)` policy matches the current `auth.uid()` or role.

Frequently Asked Questions

Why wrap auth.uid() in (select auth.uid())?
Wrapping `(select auth.uid())` allows PostgreSQL's query planner to cache the result as an initPlan once per query instead of re-evaluating it on every row.
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