# Supabase: “operator does not exist: uuid = text” (42883)
> A Supabase query or RLS policy fails with operator does not exist: uuid = text (code 42883). One side is uuid, the other text. Cast one side to match.
Canonical: https://app369.com/fix/supabase-operator-does-not-exist-uuid-text/
Last updated: 2026-11-09
“operator does not exist: uuid = text” is Postgres error 42883, raised when a query compares a uuid with a text value. Postgres won’t compare the two types on its own. In Supabase it usually shows up in an RLS policy or a storage policy, and the fix is one cast.
**Short answer**
Find the comparison in the policy, function or query, and make both sides the same type with ::uuid or ::text. auth.uid() returns a uuid, while auth.jwt() ->> 'sub' and storage folder names are text, so compare uuid with auth.uid() and text with ::text. The better long-term fix is to store user IDs in a uuid column.
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## **Where the mismatch comes from, and the fix**
1. 01 ### **A text column compared with auth.uid()**
> “auth.uid() returns the ID of the user making the request.” [**Supabase, Row Level Security**](https://supabase.com/docs/guides/database/postgres/row-level-security) auth.uid() returns a uuid. If user_id was created as text, the policy compares uuid with text and fails. The same error can read text = uuid when the sides are swapped. Change the column to uuid, or cast in the policy. Postgres won’t alter a column that a policy, view or foreign key uses, so drop those first, run the ALTER, then recreate them. On a big table the ALTER locks and rewrites it, so run it in a quiet window.```
-- best: store it as uuid
alter table posts alter column user_id type uuid using user_id::uuid;
-- or cast in the policy
create policy "own posts" on posts for select to authenticated
using ( (select auth.uid())::text = user_id );
```
2. 02 ### **Storage folder names are text**
> “Returns an array path, with all of the subfolders that a file belongs to.” [**Supabase, Storage helper functions**](https://supabase.com/docs/guides/storage/schema/helper-functions) storage.foldername() returns an array of text, so each folder name, such as (storage.foldername(name))[1], is text, and comparing it with auth.uid() fails. Compare it with a text value instead, as Supabase’s own example does.```
create policy "own folder uploads" on storage.objects for insert to authenticated
with check (
bucket_id = 'avatars' and
(storage.foldername(name))[1] = (select auth.jwt() ->> 'sub')
);
```
3. 03 ### **A value from the app arrives as text**
> “A type cast specifies a conversion from one data type to another.” [**PostgreSQL, Type casts**](https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-TYPE-CASTS) A uuid passed into an SQL function as a text parameter, or built into a query as a string, is text inside Postgres. Declare the parameter as uuid, or cast it where you compare.```
create function get_post(p_id text) returns setof posts
language sql as $$
select * from posts where id = p_id::uuid;
$$;
```
4. 04 ### **A join between two ID columns of different types**
> “The cast will succeed only if a suitable type conversion operation has been defined.” [**PostgreSQL, Type casts**](https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-TYPE-CASTS) A table built by an import or an AI tool can have one ID column as text and the matching one as uuid. Change the text column to uuid so the join, its foreign key and its index all use one type. Drop any policy, view or foreign key that uses the column first, and recreate it after the ALTER.
Checked against the vendor’s docs on November 9, 2026: [Supabase docs: Row Level Security](https://supabase.com/docs/guides/database/postgres/row-level-security); [Supabase docs: Storage access control](https://supabase.com/docs/guides/storage/security/access-control); [Supabase docs: Storage helper functions](https://supabase.com/docs/guides/storage/schema/helper-functions); [PostgreSQL docs: Type casts](https://www.postgresql.org/docs/current/sql-expressions.html#SQL-SYNTAX-TYPE-CASTS).
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Related: [**Supabase “new row violates row-level security policy”**](https://app369.com/fix/supabase-new-row-violates-row-level-security/) · [**Supabase PGRST200 (relationship)**](https://app369.com/fix/supabase-could-not-find-relationship-pgrst200/) · [**Supabase “Could not find the function” (PGRST202)**](https://app369.com/fix/supabase-could-not-find-function-schema-cache/) · [**Supabase relation does not exist (42P01)**](https://app369.com/fix/supabase-relation-does-not-exist/)
Questions
## **More on this error**
**Will casting with ::uuid fail on bad data? **+
Yes. If a text value is not a valid uuid, the cast raises an error instead of returning false. Clean up or check the values before changing a column to uuid.
**Should I cast the column or the value? **+
Cast the value from auth.uid() or the app, not the column, when you can. A cast on the column can stop Postgres from using an index on it.
**Can you fix it for me? **+
If one bug is the whole problem, the App Fix Ticket covers it: a written diagnosis first, then the fix. If the app has more going on, the Launch Check is a written check of the whole app. Each issue found is rated critical, high, medium or low, with where it is and how it was confirmed. No issues worth fixing, no charge. If the Launch Check finds nothing rated medium or higher, Simon refunds the full $450. You keep the report either way. This applies to the first 10 Launch Checks bought after October 30, 2026.
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