A TypeError: unhashable type: 'dict' in Python occurs when attempting to use a mutable object, like a dictionary, as a key in a dictionary or an element in a set, due to the requirement for keys to be hashable, or immutable. Hashable objects in Python, such as strings, integers, and tuples, have an unchanging hash value, allowing quick item location in dictionaries and sets. This error typically arises when using dictionaries as keys or when adding them to sets. Solutions include converting dictionaries to tuples or strings, restructuring data to use simple string keys, or creating a custom class to represent the data for hashable purposes. Related errors might involve dict.keys() or dict.values() due to their unhashable nature. Tools like Rollbar can assist in tracking and managing these errors by providing insights into their context and frequency, helping developers to handle them effectively.