Raised when an error occurred while doing a mass assignment to an attribute through the attributes= method. The exception has an attribute property that is the name of the offending attribute.

Methods
Attributes
[R] attribute
[R] exception
Public Class methods
new(message, exception, attribute)

Source: show | on GitHub 

     # File activerecord/lib/active_record/base.rb, line 134
134:     def initialize(message, exception, attribute)
135:       @exception = exception
136:       @attribute = attribute
137:       @message = message
138:     end