Supabase API errorSupabase: “Could not find a relationship between the tables in the schema cache” (PGRST200)

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Why the relationship is not found, and the fix

1. 01

   There is no foreign key between the tables

   “The APIs will automatically detect relationships based on the foreign keys” Supabase, Joins and nested tables

   A column called author_id isn’t enough on its own. The API follows foreign key constraints, not column names, so add the constraint.

   alter table posts
     add constraint posts_author_id_fkey
     foreign key (author_id) references profiles (id);

2. 02

   The schema cache is stale

   “Caused by stale foreign key relationships, otherwise any of the embedding resources or the relationship itself may not exist in the database.” Supabase, PostgREST error codes (PGRST200)

   A foreign key added a moment ago may not be in the API’s cached schema yet. Reload it from the SQL editor, then run the query again.

   NOTIFY pgrst, 'reload schema';

3. 03

   The name in the select is wrong

   The name inside select() has to match the table name exactly. A typo, a plural where the table is singular, or capital letters in a name Postgres stored in lowercase all give PGRST200.

   // table is profiles, not profile or Profiles
   const { data, error } = await supabase
     .from('posts')
     .select('id, title, profiles(name)');

4. 04

   Two foreign keys link the same tables

   “Choose which foreign key relationship to use when multiple foreign keys match the join.” Supabase, Joins and nested tables

   If posts has both author_id and editor_id pointing at profiles, the API can’t pick one and answers PGRST201 instead. Name the constraint to use, and give each join an alias.

   await supabase
     .from('posts')
     .select('id, author:profiles!posts_author_id_fkey(name), editor:profiles!posts_editor_id_fkey(name)');

5. 05

   The table is in another schema

   A table in a schema the API doesn’t expose isn’t in the schema cache at all. The common case is a foreign key to auth.users: the auth schema isn’t exposed, so join through a public.profiles table that references auth.users instead. For your own schemas, expose them in the API settings.

Checked against the vendor’s docs on November 9, 2026: Supabase docs: PostgREST error codes; Supabase docs: Joins and nested tables; Supabase troubleshooting: Reload the PostgREST schema; Supabase troubleshooting: Objects in an exposed schema.

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