During this project, you may encounter some common errors. 

For example, you might get some errors during building and running the project. To solve this, check that all versions of the dependencies are the latest. In addition, check whether every dependency is present. If you use the database, make sure you have the correct database and scheme name in application.properties.

In the POST request, sometimes you can find the following error message:

The previous screenshot indicates that you entered an incorrect grant_type. Please check the parameter, as well as the AuthorizationServerConfig class where you mention the grant_type:

Please check the SecurityConfiguration class and match the system username-password with the given username and password parameters. The following screenshot means you entered an incorrect client or secret value in the Basic Auth tab:

The preceding screenshot means you entered an incorrect client or secret value in the Basic Auth tab. Please match the client and secret value from AuthorizationServerConfig and the Basic Auth tab's value:

The preceding screenshot means your token key has expired. You need to refresh a new access token to solve this error.

You may face some other errors. To see the solutions, you can always search StackOverflow (https://stackoverflow.com/).