Wikipedia:Edit conflicts

Consider the following situation:

• Alice clicks "Edit this page" on a page.
• Bob clicks "Edit this page" on the same page.
• Alice finishes her edits and clicks "Save page". The page is saved with Alice's version.
• Bob finished his edits and clicks "Save page". Bob gets an "edit conflict" page.

This is discussed on this page.

Layout of the edit conflict page

At the top is Alice's version of the page.

At the bottom is the text Bob was going to submit. This will be Bob's version of the page, if he edited the entire page, or Bob's version of the section he edited, if he was editing just one section.

In the middle is a diff of the two pieces of text. This is much less useful if Bob used section editing.

Resolving an edit conflict

If Bob only made small changes, and Alice made large changes, he may choose to work from Alice's version, and re-merge his changes in. Bob might choose to add some text like "via edit conflict" to warn Alice and others that he had to do this - Alice can then peer review his merging for accuracy.

If Bob made large changes, and Alice made small changes, he may choose to work from his version. One option is for Bob to copy the bottom text into the top text (or just copy over the one section of the top text, if Bob was section editing), with an appropriate edit summary (eg "via edit conflict, will remerge"). Then Bob can view the page history, determine Alice's changes, and re-apply them to his version, in a separate edit.

If both Alice and Bob made large changes, matters become complicated, and Alice and Bob just have to do the best they can. For example, if both Alice and Bob simultaneously add a large section of text on the same subject, then it may be best for Bob to submit his changes, and then for Alice and Bob to both have a look at the two versions and decide between themselves which version is better.

Bob must not just post his changes over the top of Alice's. We assume good faith here - mistakes are occasionally made, and newcomers may not understand the edit conflict window. However, routinely ignoring edit conflicts is in direct breach of our official policy on Wikiquette and WikiLove. It is absolutely not acceptable for Bob to overwrite Alice out of a desire to get his edit through without having to merge it with Alice's. We encourage contributors to double-check their merges by using the diff feature.

Logical edit conflicts

Some people edit by copying the source text into a text editor, making lots of changes (reorganising, adding new content, etc), and then, when they're done, pasting the whole thing back onto Wikipedia as a single edit. If someone has made minor changes prior to their paste-back, sometimes these changes can get lost in the paste back. People who edit in this manner should check the diff on their edit to make sure they didn't inadvertantly blast over the top of someone else's changes.

Mistakes

Sometimes mistakes will be made in the merging process, because Bob is human, and this may cause some of Alice's changes to be accidentally reversed. Logical edit conflicts aren't always immediately visible. Sometimes Bob may have good reasons for thinking that Alice's improvements aren't useful. In these case, Alice and Bob are expected to resolve their differences amicably.

If Alice made a small change, which Bob accidentally reversed, then Alice must not revert to her version. Doing so is in direct breach of our official policy on Wikiquette and WikiLove. It is absolutely not acceptable for Alice to reverse Bob's major improvements to the page out of a desire to protect her minor improvements, or to punish Bob for his carelessness. This is particularly important if the page has subsequently been edited by, say, Carol and David.

The best approach for Alice in this circumstance is for Alice to edit Bob's version, reinstate her minor improvements, and leave Bob's major improvements intact. She may also add something to the edit summary to indicate that she had to do this - for example: "Reinstating link which Bob accidentally removed". Bob should then apologise to Alice for his mistake, and thank her for reinstating her improvement.

Reverting

When saving a previous version (i.e. when reverting) or a new version based on that (a modified reversion) the edit conflict warning and prevention system is not triggered and a possible new edit made in the meantime is unintentionally reverted also, see Wikipedia:How to revert a page to an earlier version. To avoid this problem one can copy the text from the edit box of the old version into the edit box of the latest version (for just a reversion this is probably not needed because it is so fast that an edit conflict is unlikely).

Prevention

Because edit conflicts are irritating and time-consuming, you may choose to alter your editing habits to render them less frequent: aiming to make more edits to pages that have not been edited recently, such as those listed on ancient pages, for example.

Another means of avoiding edit conflicts is to make a single larger change, rather than frequent smaller changes: this makes it more likely that you will get an edit conflict, but less likely that you will cause others to get an edit conflict. Using the "Show preview" button helps here.

In the long term, some form of automatic merge may be added to the WikiMedia software.