Fix · Supabase and databases

duplicate key value violates unique constraint (23505)

What you may see

Saving fails because something with the same value already exists

Most likely cause

A column that must be unique (an email, a slug, an order number) already holds this value.

Check first (about two minutes)

Read the constraint name in the message: it tells which column.

The fix prompt

What you type here never leaves your browser. The search runs on this page, and nothing is sent to a server or to an AI.

The exact error or what you see

What you did before it happened

Kept only in this browser, on this device. Keys and passwords are removed before anything is saved.

Prompt language

You are a careful senior engineer who knows Supabase (database, login and file storage) and explains it to people who are not developers. I am not a developer, so explain every step in plain words and tell me exactly which button, menu or command you mean. If you are not sure about something, say so; do not guess.

THE PROBLEM
duplicate key value violates unique constraint (23505)

THE EXACT ERROR OR WHAT I SEE
[paste the exact error here]

WHAT I DID BEFORE IT HAPPENED
[write in a few words what you did before it happened]

MOST LIKELY CAUSE
A column that must be unique (an email, a slug, an order number) already holds this value.

DO THESE STEPS, IN THIS ORDER
1. Find which column and which existing row clash.
2. Decide with me: update the existing row (upsert), choose another value, or show a friendly message.
3. Make the code handle this error with a clear message.
Stop and tell me if what you see does not match a step. Do not skip ahead.

CHECK THAT IT WORKED
- Saving the same value twice shows the friendly message and does not create a duplicate.
Tell me exactly what I should see on the screen when it works.

DO NOT CHANGE
- Do not remove the unique rule.
- Anything I did not ask about: the design, the text, other pages, other settings or the data.
- Do not delete files, data or branches, do not reset or force-push, and do not rewrite history, unless you first show me exactly what would be lost and I say yes.
- Do not paste, print or ask me to paste a password or secret key into this chat. If one is needed, tell me which settings page of the right service to store it in.

WHEN YOU FINISH
Explain in simple words what you changed (file by file or setting by setting), why you changed it, and how I can undo it.

Paste it into Claude, ChatGPT, Gemini or Cursor, then follow what it says.

After you tried it, did it work?

Steps

Find which column and which existing row clash.
Decide with me: update the existing row (upsert), choose another value, or show a friendly message.
Make the code handle this error with a clear message.

Do not do this

Do not delete the old row without checking what depends on it.
Do not remove the unique rule.

Try another entry