Description

A large page with a lot of markup (tables with layouts and stuff mainly) has the text corrupted in small and terrible ways on updates sometimes. This usually means small fragments of text (3-10 characters) from one point in the document apparently randomly plopped into another part of the document. We don't use any WYSIWYG editor and the user has been editing the wiki for years without problems.

Steps to reproduce

Unfortunately I'm not sure how to reproduce it reliably yet; it has only occured on one page (the largest and most complex) page in my wiki, usually in the table sections.

Example

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev1=78&rev2=77 shows corruption being removed on line 588 and introduced on line 852

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev2=79&rev1=78 More corruption introduced on line 851

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev1=80&rev2=79 Corruption introduced on line 852 again

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev2=81&rev1=80 Again line 852

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev1=82&rev2=81 Corruption introduced on lines 214 and 585

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev2=83&rev1=82 Line 587

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev2=89&rev1=88

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev1=90&rev2=89

• http://alopex.li/wiki/PnPFE/v8?action=diff&rev1=92&rev2=91 line 816

• And more, see change history

Component selection

• general, markup parser or output

Details

Workaround

Current workaround is keeping the whole wiki page in a separate file on the user's computer and copy-pasting the whole thing into the text box on each update. At least this means the corruption doesn't build up over multiple edits.

Discussion

Very strange. If it only happens to one user, I would look for other strange events happening on the same PC or the hardware between that PC (routers, etc) and the server. I have seen low voltages cause very flaky, impossible to reproduce results. If you can easily swap the user's PC I would try that first to see if the problem continues. What browser is being used?

• That's something I hadn't considered; the user was on pretty bad internet at the time and now that I check I can't find edits by any other user that introduce problems. He is using Opera; I will tell him to try more edits and see if the problem recurs, then try Chrome or such if it does, and report back. -- Simon

If it only happens for that one user (that one PC, that one browser) and not on other client machines, then first try other browser (or older/newer version of Opera). If that doesn't fix it, check your hardware (run memtest86+ for at least 1 full pass). It doesn't very much sound like a moin problem (as that likely would happen for all users / all client machines).

• Note that it is possible to experience incomplete pages with Moin where the page doesn't finish loading, but where the editing text box is usable and contains some of the page text, because the user can edit the incomplete text, click "Save Changes", and the browser (Iceweasel/Firefox, at least) will happily send the incomplete text back as the updated page text to be saved. That doesn't explain random relocations of text, though. -- PaulBoddie 2013-10-30 10:34:24

• Okay, the weird corruption occurred again on a recent edit by the same user; I've asked him to try on a different computer/browser next time and see if that changes anything. -- Simon 2013-11-03

Plan

• Priority:
• Assigned to:
• Status: likely an issue of client hard- or software, not a moin / server issue

CategoryMoinMoinNoBug