Supabase Debug

Supabase Debugging Patterns

Quick-reference debugging skill for Supabase-backed projects (9/11 active projects use Supabase).

Common Issues & Fixes

Empty Data / Missing Records

Symptom: Query returns empty array but data exists in DB

1. Check RLS policies - most common cause

   -- View policies on a table
   SELECT * FROM pg_policies WHERE tablename = 'your_table';
   

2. Check auth state - is user authenticated-

   const { data: { user } } = await supabase.auth.getUser();
   console.log('Auth state:', user?.id, user?.role);
   

3. Check tenant filtering - multi-tenant apps filter by company_id

   // Verify the company_id matches
   const { data } = await supabase.from('table').select('*').eq('company_id', companyId);
   

Auth Issues

Symptom: 401 Unauthorized, session expired, login loops

1. Check if token is expired: supabase.auth.getSession()
2. Verify redirect URLs in Supabase dashboard match app URL
3. For OAuth: check provider settings in Supabase Auth config
4. Clear local storage and re-authenticate

RPC / Edge Function Failures

Symptom: Function call returns error or unexpected result

1. Check Supabase dashboard -> Edge Functions -> Logs
2. Verify function exists and is deployed: supabase functions list
3. Check function has correct permissions (auth required vs public)
4. Test directly: curl -X POST <supabase_url>/functions/v1/<function_name>

Migration Issues

Symptom: Schema mismatch, missing columns/tables

1. Check migration status: supabase migration list
2. Run pending: supabase db push
3. If stuck: check supabase/migrations/ for conflicting files
4. Nuclear option: supabase db reset (WARNING: destroys data)

Real-time Subscription Not Working

Symptom: UI not updating when data changes

1. Verify Realtime is enabled for the table in Supabase dashboard
2. Check subscription filter matches: .on('postgres_changes', { event: '*', schema: 'public', table: 'your_table' })
3. RLS applies to realtime too - check policies
4. Check browser console for WebSocket errors

Quick Diagnostic Commands

# Check Supabase project status
npx supabase status

# View recent logs
npx supabase functions logs <function-name> --tail

# Test RLS as a specific user
npx supabase db test

# Check table structure
npx supabase db dump --schema public | grep "CREATE TABLE your_table" -A 20

Project-Specific Notes