Understanding Invalid Database Credentials Error

When developing applications that rely on a database, encountering an invalid database credentials error is a common hurdle. This error typically occurs when the provided credentials—such as username, password, or database name—do not match the information stored in the database management system. Here are three practical examples to help you identify and troubleshoot this issue.

Example 1: Incorrect Username

Context

In a web application that connects to a MySQL database, a developer may mistakenly use the wrong username due to a typographical error.

Example

When trying to connect to the database, the following error message is returned:

Error: Access denied for user 'wrong_user'@'localhost' (using password: YES)

This indicates that the application attempted to log in using ‘wrong_user’, which does not exist in the MySQL database.

Notes

• Double-check the username for any spelling mistakes.
• Ensure that the user is created in the database and has the necessary privileges.

Example 2: Mismatched Password

Context

In a Node.js application using PostgreSQL, a developer might forget to update the password after a security change.

Example

Upon trying to establish a connection, the application throws this error:

Error: password authentication failed for user "correct_user"

This error suggests that the password supplied for ‘correct_user’ is incorrect.

Notes

• Verify that the password in your code matches the password in the database.
• Consider using environment variables to store sensitive information securely.

Example 3: Database Name Error

Context

In a Java application, a developer may inadvertently refer to a non-existent database when setting up the connection.

Example

The following error message surfaces when attempting to connect:

Error: Unknown database 'non_existent_db'

This indicates that the specified database does not exist on the server.

Notes

• Ensure that the database name is correctly spelled and case-sensitive, as some database systems treat names differently.
• If the database should exist, check whether it was created successfully during the setup process.