is not known to the MapperRegistry.

This error message usually occurs in frameworks that use object-relational mapping (ORM) libraries such as Hibernate or MyBatis. It means that the ORM library cannot find the mapping configuration for the entity object, which is required to map the properties of the object to database columns.

To solve this error, you can check the following:

1. Make sure that the entity class is correctly annotated with the ORM annotations, such as @Entity, @Table, @Column, etc.

2. Ensure that the mapping configuration file (such as hibernate.cfg.xml or mybatis-config.xml) is correctly configured to include the entity object.

3. Check if the mapping file is in the correct location and properly named.

4. Verify that the database connection properties are correctly set in the configuration file.

5. Check if the database schema is correctly configured and the tables corresponding to the entity objects exist in the database.

By resolving any of the above issues, you should be able to fix the error and successfully map the entity object to the database table.