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    • CommentRowNumber1.
    • CommentAuthorTodd_Trimble
    • CommentTimeMar 17th 2016

    I noticed something weird: when at the page injective object, the address bar shows https://ncatlab.org/nlab/show/injective%20object (with a space between “injective” and “object”, instead of “injective+object”). When I crosslinked to a subsection of this page during an edit, this produced a Bad Gateway message upon submission, until I realized the missing +.

    Any idea how that could happen?

    • CommentRowNumber2.
    • CommentAuthorMike Shulman
    • CommentTimeMar 18th 2016

    In my experience, the nLab doesn’t seem to care whether words in page names are separated by +s or spaces in the URL. I don’t think I’ve ever seen it display as %20 rather than a space, and right now if I put in a %20 manually then it turns into a space (Firefox 44).

    • CommentRowNumber3.
    • CommentAuthorUrs
    • CommentTimeMar 18th 2016
    • (edited Mar 18th 2016)

    All three cases (” “, “+” “%20”) should be and were treated the same. But since some time now, BadGateway error messages appear all over the place where previously the software would have known how to handle a URL. I had commented on that in another thread some time back.

    On my system, sometimes changing the browser helps. Or closing it and re-opening it.

    In any case, with some recent update something must have broken in Instiki, something that used to work and is now causing spurious errror messages to appear. I had alerted Adeel and others of this a while back, but I suppose nobody has yet found the time or energy to do anything about it (which might mean: contact Jacques Distler about it).

    • CommentRowNumber4.
    • CommentAuthorTodd_Trimble
    • CommentTimeMar 18th 2016

    Okay, thanks. I’ll just comment that when I did insert + into the link, the Bad Gateway message went away and the link worked.

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeMar 18th 2016

    Okay, thanks. We might want to do more experimenting to be able to give Jacques a better idea for what might be going on.

    Did you try whether with another browser it still worked even without the hack? Or closing the browser and opening it again? For me this tends to make the funny error messages go away, which should be a hint as to what might be going on.

    • CommentRowNumber6.
    • CommentAuthorZhen Lin
    • CommentTimeMar 18th 2016
    • (edited Mar 18th 2016)

    If I recall correctly, strictly speaking + and %20 are not interchangeable in URLs. In the query part (i.e. the part after ?) they are usually interchangeable. For better or worse, recent versions of Firefox and other browsers tend to display URLs with percent-encoded characters decoded; if you try to copy them to the clipboard you will get the actual form.

    • CommentRowNumber7.
    • CommentAuthorTodd_Trimble
    • CommentTimeMar 18th 2016

    The %20 didn’t actually appear in my address bar; but it was produced here when I copied the URL and pasted it here.

    • CommentRowNumber8.
    • CommentAuthorTobyBartels
    • CommentTimeMay 23rd 2016

    Reportedly, Google recommends never using the plus sign, only a space, although I'm not able to read the original recommendation. (%20 should be perfectly equivalent to a space, while + is technically different; on the other hand, %2B and %2b should each be perfectly equivalent to +.) Internal double-bracket links from the Lab produce a plus sign, while double-bracket links from the Forum produce a space.