How to fix auth/invalid-creation-time: Creation time must be valid UTC date string in Firebase

FirebaseINTERMEDIATEMEDIUMUpdated Dec 12, 2025· 179 views

This Firebase Authentication error occurs when you attempt to create or update a user with an invalid creation time timestamp.

Quick fix

Fixes auth/invalid-creation-time

  1. Verify timestamp format
  2. Convert timestamps
firebase — error
# auth/invalid-creation-time: Creation time must be valid UTC date string
auth/invalid-creation-time: Creation time must be valid UTC date string

What this error means

The error indicates your application is trying to set a user's creationTime field with a value that doesn't conform to Firebase's required UTC date format.

Typical symptoms

  • Firebase Admin SDK throws error when calling createUser() or updateUser()
  • User migration scripts fail with timestamp validation errors

Common causes

  1. Providing a non-UTC timestamp string
  2. Using local time format instead of UTC

How to fix "auth/invalid-creation-time: Creation time must be valid UTC date string"

1Verify timestamp format

Use ISO 8601 UTC format ending with "Z".

2Convert timestamps

Convert existing timestamps to proper UTC format.

Advanced notes

Firebase requires UTC timestamps in ISO 8601 format.

Frequently asked questions

What does "auth/invalid-creation-time" mean?
The error indicates your application is trying to set a user's creationTime field with a value that doesn't conform to Firebase's required UTC date format.
How do I fix "auth/invalid-creation-time"?
This Firebase Authentication error occurs when you attempt to create or update a user with an invalid creation time timestamp.
What causes "auth/invalid-creation-time"?
Providing a non-UTC timestamp string Using local time format instead of UTC
Is the "auth/invalid-creation-time" error serious?
It is a medium-severity error — more of a blocker than a risk. The steps above resolve it.

Official resources & further reading