Wikipedia:Stable version
The stable version is the most recent revision of an article that was not affected by an active content dispute or edit war. Restoring an article to the stable version when fully protecting it (in response to such a content dispute or edit war) is a common administrative practice that is authorized by the Protection policy. Restoring the stable version is not required or encouraged by any policy or guideline, and administrators can fully protect articles mid-dispute, even if the protected version contains controversial edits. However, doing so can upset editors who did not get their preferred version protected, and they may complain that the admin has protected "the wrong version". Reverting to the stable version returns the article to neutral ground, and thus may help de-escalate a situation better than protecting one party's preferred version would. Administrators should consider what the best course of action is on a case-by-case basis, and neither option constitutes an admin's involvement in a dispute or an endorsement of the protected version of an article in any way. If an administrator protects an article without restoring the stable version, editors can still request that the stable version be restored by any administrator.
Inappropriate usage
It is important to note that outside of the limited administrative context, a "stable version" is an informal concept that carries no weight whatsoever, and it should never be invoked as an argument in a content dispute. Maintaining a stable version is, by itself, not a valid reason to revert or dispute edits, and should never be used as a justification to edit war. Stable versions are not superior or preferred to disputed edits in any way, boldly making changes to articles is encouraged as a matter of policy, and obstructing good faith edits for the sake of preserving "stable" content is a form of disruptive editing. Editors involved in content disputes or edit wars should focus on resolving the dispute, rather than preserving the stable version, and the decision to temporarily preserve the stable version for the purposes of deescalating a dispute may only be made by an uninvolved administrator.
Editors who persistently attempt to enforce a stable version may be blocked from editing without warning.
Historical usage
Historically, the phrase "stable version" was used to refer to a wide variety of proposals to implement a formal system to identify and maintain good-quality versions of articles—keeping them "stable" from any potential unwanted changes. Such proposals included Stable versions, Stable versions now, Stabilizing featured articles, Baseline revision, Article validation, Reviewed versions, Community assent, Flagged revisions, and Pending changes. After many years of debate and controversy over "flagged revs", the variation of these proposals known as pending changes protection was permanently implemented in December 2012 and remains in effect to this day. The term "stable version" is no longer used in this context.