Error Code Portal
GoogleFirebase Authentication Admin SDKError code

auth/uid-already-exists

uid already exists

What does this code mean?

Code auth/uid-already-exists · An issue reported by Firebase Authentication Admin SDK.

Official explanation · Original text

The provided uid is already in use by an existing user. Each user must have a unique uid.

Troubleshooting and diagnostic links

First check that the document's product, version, and environment match your situation.

Source and terms of use

Firebase Admin Authentication API Errors ↗

Creator: Google LLC
License: Creative Commons Attribution 4.0 International
Checked on: 2026-11-12

Modifications: Extracted official error code and description/resolution table; HTML stripped; short code name and original Korean context added. No source-page analytics scripts are redistributed in rendered pages.

Source details · Original licenses and notices