How to fix 42P01: Undefined table in Supabase

Open Supabase Dashboard and navigate to the SQL Editor. Run this query to list all tables in the public schema:

SELECT table_name 
FROM information_schema.tables 
WHERE table_schema = 'public' 
ORDER BY table_name;

Check if your table name appears in the results. If it doesn't, the table doesn't exist yet.

Carefully compare the table name in your error message with the actual table name in your database. PostgreSQL is case-sensitive for quoted identifiers:

- If your table is named users (lowercase), reference it as users
- If your table is named "Users" (quoted), you must always use quotes: SELECT * FROM "Users"
- Without quotes, PostgreSQL converts to lowercase: Users becomes users

Check your schema or migrations file for the exact table definition.

If you recently created migrations, they may not have been deployed yet. Use Supabase CLI to push migrations:

supabase db push

If using the dashboard only, migrations are applied immediately. If using Supabase CLI locally, you must explicitly push them to your project with the command above. Verify the migration succeeded by checking the tables again.

If your table is in a schema other than public, you must specify the schema:

SELECT * FROM your_schema.your_table;

View all schemas:

SELECT schema_name 
FROM information_schema.schemata;

For Supabase Auth tables, use the auth schema:

SELECT * FROM auth.users;

If your table name has uppercase letters, you must quote it every time:

// Incorrect - will fail if table is "UserProfiles"
const { data } = await supabase
  .from('UserProfiles')
  .select()

// Correct - use double quotes to preserve case
const { data } = await supabase
  .rpc('your_function', {})

// Or use all lowercase and create table as lowercase
const { data } = await supabase
  .from('user_profiles')
  .select()

Best practice: Always create tables with lowercase names using underscores (snake_case) to avoid quoting issues.

Sometimes a table exists but Row Level Security (RLS) policies prevent you from seeing it. Check RLS settings:

1. Go to Supabase Dashboard > Authentication > Policies
2. Select your table from the dropdown
3. Verify policies allow SELECT access for your user role

If no policies exist, RLS may be disabled (which is fine). If policies exist but don't grant access, add a policy:

CREATE POLICY "Allow public select" ON your_table
FOR SELECT USING (true);