MyBatis Update Error: Parameter 'userName' Not Found - Troubleshooting Guide

This error is caused by a missing parameter in your MyBatis update statement. The parameter 'userName' is not found in the statement, and the available parameters are [arg0, collection, list].

To resolve this issue, you need to make sure that the parameter 'userName' is correctly defined and passed in the update statement. Double-check the parameter name and ensure that it matches the parameter name in your XML mapper file.

Here is an example of how the update statement should look like in your userMapper.xml file:

<update id="updateAll" parameterType="your.package.User">
  UPDATE users
  SET username = #{userName},
      -- other fields to update
  WHERE id = #{id}
</update>

Make sure that the parameter name 'userName' matches the property name in your User class.