Edit conflict

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In certain situations, two users may try to edit the same page at the same time. If this happens, the second person to attempt to save the page will cause an edit conflict — that is, a conflict between two different saved versions of the same page. Consider the following sequence of events:

1. Adam clicks the "edit this page" button, and begins editing an article.
2. Beverly clicks the "edit this page" button, and begins editing the same article.
3. Adam saves his version of the article.
4. Beverly tries to save her version of the article, which is different from Adam's version.

In cases such as these, several things can happen. First, the MediaWiki software will attempt to merge the two versions of the page. Using the diff3 utility, MediaWiki can combine the two versions of the page — provided that Adam and Beverly each changed different parts of the article. However, Adam and Beverly might have made different changes to the same part of the article. The rest of this page will address the second situation.

Conflict warning page

If MediaWiki cannot merge the two versions of the page on its own, it will bring up a "conflict warning" notice when Beverly tries to save her version of the article, because Adam has already saved his version. The conflict warning notice contains three parts: first, at the top is shown Adam's version of the page. At the bottom, the version that Beverly was trying to submit is shown. In the middle, a colored table shows the differences between the two versions.

How to resolve a conflict

Resolving an edit conflict is always a value judgment. Beverly must choose whether to integrate her changes with Adam's version, or Adam's changes with her version. In either case, she can then add some text like "via edit conflict" in the edit summary to warn others that she had to integrate the changes.

If both Adam and Beverly made large changes to the article, the situation is more complicated. Sometimes, it may just be best to temporarily add both versions of the text, and to merge them later on after some discussion on the article's talk page.

In all cases, Beverly should never simply post her own changes on top of Adam's. Such an act is unfair to Adam because it erases the work he just completed, and is therefore considered bad etiquette.

"In use" message

For convenience, the Retro wikis includes the option of posting an "in use" message at the top of a page. Simply paste the string {{inuse}} at the top of the wikitext and save the page; this will inform people who come after you that you are in the process of editing the page, and help to avoid edit conflicts. (This should generally only be used for large edits, however.)