A hotfix or Quick Fix Engineering update (QFE update) is a single, cumulative package that includes information (often in form of one or more files) that are used to address a problem in a software product (i.e. a software bug). Typically, hotfixes are made to address a specific customer situation and may not be distributed outside the customer organization. The term hotfix was originally applied to software patches that were applied to live i.e. still running systems. Similar use of the terms can be seen in hot swappable disk drives. The more recent usage of the term is likely due to software vendors making a distinction between a hotfix and a patch.
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