MongoDB Atlas Authentication Failed (bad auth)

How to fix it

Try these in order — the most common fix is first.

1. 1. Use a database user

   Copy steps
   1. Open Security > Database Access
   2. Check the user exists with a role that fits (e.g. readWriteAnyDatabase)
   3. Edit the user and set a new password if unsure
   Did this fix it? Yes No

2. 2. Percent-encode the password

   Copy steps
   1. Encode : / ? # [ ] @ ! $ & ' ( ) * , ; = % and spaces, e.g. p@ss becomes p%40ss
   2. In Node use encodeURIComponent(password); in Python quote_plus(password)
   3. Do not encode when typing the password into mongosh's prompt
   Did this fix it? Yes No

3. 3. Set authSource

   1. Add ?authSource=admin to the URI (or the database where the user was created)
   Did this fix it? Yes No

4. 4. Copy a fresh string

   1. Click Connect on the cluster, choose Drivers, and replace <password> with your database user's password (without the angle brackets)
   Did this fix it? Yes No

Symptoms

MongoServerError: bad auth : Authentication failed (code 8000), or 'Authentication failed' in Compass, mongosh or your driver.

Why it happens

• Using the Atlas account email/password instead of a database user
• Wrong password or user for this project
• Unencoded special characters (@ : / ? # etc.) in the URI
• Wrong authSource
• User was edited and not yet applied or was deleted

This guide also covers

• mongodb atlas authentication failed
• mongoservererror bad auth
• mongodb atlas bad auth authentication failed
• mongodb password special characters

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• MongoServerSelectionError: Fix for MongoDB Atlas
• MongoDB querySrv ENOTFOUND / ECONNREFUSED Error
• MongoDB Atlas Free Tier (M0) Limits and Throttling
• MongoDB Atlas Cluster Paused (Resume or Auto-Pause)
• MongoDB Atlas Unexpected Bill: Why It's So High
• MongoDB Atlas Too Many Connections Error
• MongoDB Atlas AWS VPC Peering Not Connecting