Fix · Supabase and databases

File upload to Supabase Storage fails

Blocks your workNot checked against the vendor's current screens

What you may see

Uploading an image or file gives an error or never finishes
It says bucket not found or row-level security

Most likely cause

The bucket name is wrong or missing, the storage policies do not allow this user to upload, or the file is above the size or type limit.

Check first (about two minutes)

Open Storage in the dashboard: does the bucket exist with exactly that name?
Check the file size and type against the bucket's limits.

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.

Menu and button names change over time. If you cannot find a button or page I mention, say so and tell me what to look for instead of guessing.

THE PROBLEM
File upload to Supabase Storage fails

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
The bucket name is wrong or missing, the storage policies do not allow this user to upload, or the file is above the size or type limit.

DO THESE STEPS, IN THIS ORDER
1. Read the exact error and the upload code (bucket name, file path, file type, size).
2. Check the bucket exists, and whether it is public or private.
3. Check the storage policies (on storage.objects) allow insert for this user into this path only; write the narrow policy as a migration if missing.
4. Resize big images in the browser before upload and show a clear error for wrong types.
Stop and tell me if what you see does not match a step. Do not skip ahead.

CHECK THAT IT WORKED
- A test image uploads, and can be shown (public) or opened with a signed address (private).
Tell me exactly what I should see on the screen when it works.

DO NOT CHANGE
- Do not make a private bucket public to make uploads work.
- 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

Read the exact error and the upload code (bucket name, file path, file type, size).
Check the bucket exists, and whether it is public or private.
Check the storage policies (on storage.objects) allow insert for this user into this path only; write the narrow policy as a migration if missing.
Resize big images in the browser before upload and show a clear error for wrong types.

Do not do this

Do not let anyone upload anywhere in the bucket.
Do not make a private bucket public to make uploads work.

Try another entry