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    • CommentRowNumber1.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017

    I am struggling with “500 Internal Server Errors” that appear when saving and/or displaying the notes the I am writing.

    I have been trying hard to determine what exact line causes the error, but I don’t recognize any systematics.

    I was suspecting that it has to do with equation references as in

      (eq:EquationName)
    

    but I can’t isolate this as the source of the problem.

    First I get the errors upon saving (after hitting “submit”) but after a while they also affect content that was previously already saved succesfully.

    For instance right now on my sytem just asking the Sandbox to display produces a “500 Internal Server Error”.

    • CommentRowNumber2.
    • CommentAuthorDavid_Corfield
    • CommentTimeOct 10th 2017

    Sandbox is displaying for me right now.

    • CommentRowNumber3.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017

    Thanks. Yes, the page now displays on my system, too. Unfortunately, I still get the internal server error when trying to save my new version. This is very frustrating…

    • CommentRowNumber4.
    • CommentAuthoradeelkh
    • CommentTimeOct 10th 2017

    It’s displaying for me as well, but I was able to verify your issues with saving. It looks like a Maruku bug, I’ve reported it so we’ll see what happens.

    • CommentRowNumber5.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017

    And in fact right now, right after trying to save the expanded version, also showing the page gives me an Internal Server Error again.

    • CommentRowNumber6.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017

    I can reproducibly trigger a “500 Internal Server Error” by writing

     (eq:EquationName)
    

    when “EquationName” has not been defined. That’s why I speculated it has something to do with this.

    • CommentRowNumber7.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017
    • (edited Oct 10th 2017)

    Okay, I have now removed all

    (eq:
    

    from my code, and now it does save. Now I only have to find in which of 69 occurences I have a misprint…

    • CommentRowNumber8.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017
    • (edited Oct 10th 2017)

    I have gotten closer, maybe somebody can help me:

    I have turned all occurences of

      (eq:something
    

    into

       (eqs:something
    

    to make the parser skip them, and then I re-introduced them one-by-one to see which one is the first to cause a problem.

    The first one that causes the problem is the one in the line

      Now we regard this as a _[[graded module]]_ over $\Omega^{0,0}_{\Sigma,cp}(E,\varphi)$ (eqss:FunctionsOnInfinitesimalNeighbourhoodOfBackgroundSolution) concentrated in degree $-1$:
    

    But the problem is not that the anchor

      FunctionsOnInfinitesimalNeighbourhoodOfBackgroundSolution
    

    is undefined. It seems properly defined.

    If anyone wants to give it a try: take the page source here and try to replace the occurence of

      (eqss:
    

    or the following occurences of

      (eqs:
    

    into proper

      (eq:
    

    Can you do it so that the output works? Or else, what needs to be changed for this to happen?

    (Best to do this in the Sandbox, but presently the Sanbox again gives me Internal Server Error no matter what.)

    geometry of physics – A first idea of quantum field theory.

    • CommentRowNumber9.
    • CommentAuthorTim_Porter
    • CommentTimeOct 10th 2017

    In case it helps : I tried Sandbox and it worked fine. Then I tried Sandbox2 and got the error message. Now 5 minutes later Sandbox2 works fine.

    • CommentRowNumber10.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017
    • (edited Oct 10th 2017)

    Thanks, Tim. Right, what makes this really fiddly to pin down is that there is some time dependency involved.

    For instance I just tried resaving the entry at geometry of physics – A first idea of quantum field theory and what previously worked gave me an error message now! So now I turned one more occurence of

      (eq:
    

    into

      (eqs: 
    

    to make it work. Sigh.

    • CommentRowNumber11.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017

    But Tim, if you have energy to help: What happens to you when you open the Sandbox and replace the first occurence of

      (eqs:
    

    with

      (eq:
    

    ?

    • CommentRowNumber12.
    • CommentAuthorTim_Porter
    • CommentTimeOct 10th 2017
    • (edited Oct 10th 2017)

    I replaced the first one that I found, which was (eqs:ConstantSectionOfTrivialShellBundle), …no problem. Then I replaced the next one which was (eq:FunctionsOnInfNbh) and I got the error.

    Update: that may have been wrong as I found another (eqs:ConstantSectionOfTrivialShellBundle and editing that gave Error 502 Ray ID: 3ab8f03d7a530b7b • 2017-10-10 10:37:00 UTC and said it was an error that was at ncatlab.org.

    I have replaced eq by eqs back in those two situations, but it still is giving 502. I cleared my local cache just to make sure and also tested on Safari. Same result . (I did not think it was a browser issue merely wanted to check I was not calling up some faulty version from my cache.)

    I should perhaps point out that the errors I am getting are ‘Bad Gateway’ ones (502) not internal server error (500).

    I made some other changes to another entry and there was no problem.

    (Edited 38 minutes later: Has someone done something? I was unable to see the Sandbox after my edits. Now I can.)

    • CommentRowNumber13.
    • CommentAuthorTim_Porter
    • CommentTimeOct 10th 2017
    • (edited Oct 10th 2017)

    Perhaps further progress: I tried to see if there was a case somewhere of an (eq which worked. I tried to search in the Lab for (eq and this is what I got:

    Oops! Please report this on the nForum (in the Technical category), giving as precise details as you can as to what triggered the error.

    and a

    500 Internal Server Error

    • CommentRowNumber14.
    • CommentAuthorUrs
    • CommentTimeOct 10th 2017
    • (edited Oct 10th 2017)

    Tim, thanks for your efforts!

    At least you are seeing the same kind of erratic behaviour as I get on my side, that’s already good to know.

    Adeel says he has reported this as a bug now.

    • CommentRowNumber15.
    • CommentAuthoradeelkh
    • CommentTimeOct 10th 2017

    I think it might be fixed now. Can you check if you’re still getting errors?

    • CommentRowNumber16.
    • CommentAuthorDavidRoberts
    • CommentTimeOct 10th 2017

    I tried editing David Roberts (to add one extermal link) and I get a 500 sever error. When I tried to cancel the edit I get

    XML Parsing Error: junk after document element Location: https://ncatlab.org/nlab/show/David+Roberts Line Number 3, Column 1:
    
    <p>Back to the <a href="/">Home Page</a>.</p>
    ^
    
    • CommentRowNumber17.
    • CommentAuthorMike Shulman
    • CommentTimeOct 11th 2017

    I’m getting that XML parsing error on trying to view a bunch of pages, like category theory.

    • CommentRowNumber18.
    • CommentAuthorTim_Porter
    • CommentTimeOct 11th 2017
    • (edited Oct 11th 2017)

    I just looked at over category from a Google search and got

    XML Parsing Error: junk after document element Location: https://ncatlab.org/nlab/show/over+category Line Number 3, Column 1:

    so something is sick out there!!!

    Other articles seemed to work alright. (Edit: I tell a lie!!!! Several other articles called up from a Google search page gave the same error.)

    • CommentRowNumber19.
    • CommentAuthorUrs
    • CommentTimeOct 11th 2017
    • (edited Oct 11th 2017)

    While in Sandbox all the

      (eqs:EquationLabel)
    

    got changed back to the proper

      (eq:EquationLable)
    

    without producing an error, now none of the equation numbers get rendered: all the “(eq:EquationLabel)” appear verbatim in the output text.

    Also, every numbered equation carries the same number “(1)”, at the moment.

    • CommentRowNumber20.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017

    Oops. That XML parsing error should be fixed now, but I’m not sure why the Maruku “fix” broke the equation numbers.

    • CommentRowNumber21.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017

    Ok, I think it is fixed now. All the equation numbers are rendering except (eq:FunctionsOnInfinitesimalNeighbourhoodOfBackgroundSolution), which indeed doesn’t seem to be defined (presumably FunctionsOnInfNbh was intended).

    • CommentRowNumber22.
    • CommentAuthorUrs
    • CommentTimeOct 11th 2017

    Thanks, Adeel!

    Sorry, but one more thing: now none of the maths is rendered anymore…

    • CommentRowNumber23.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017

    I temporarily broke all the math everywhere for a moment, should be back to normal now…

    • CommentRowNumber24.
    • CommentAuthorUrs
    • CommentTimeOct 11th 2017

    That was quick!

    Sorry again: now on re-saving I again get the “500 Internal Server Error”.

    • CommentRowNumber25.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017

    Sorry, I was in the middle of making the temporary fix more permanent and some unexpected complications arose. Anyway, I believe everything should be working now (and I’m not going to touch anything for a bit unless you point out otherwise).

    For the record, the nLab is now using this forked version of Maruku.

    • CommentRowNumber26.
    • CommentAuthorUrs
    • CommentTimeOct 11th 2017

    Thanks, Adeel!

    The test case in the Sandbox seems to be working perfectly now!

    But, sorry to still bother you, other entries pointed out above now produce the “500 Internal Server Error” message, for instance category, topos, ring.

    (?)

    • CommentRowNumber27.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017
    • (edited Oct 11th 2017)

    Hm, that’s pretty bad. I’ll have to revert the change I made then for now (so the equation reference issues will be back again).

    [edit: going to try something, give me a couple minutes]

    • CommentRowNumber28.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017

    Ok, I did not mean to spend that long on this… but I think it might really be fixed now. At least, Sandbox, category, topos and ring are all working.

    • CommentRowNumber29.
    • CommentAuthorUrs
    • CommentTimeOct 11th 2017

    Adeel, you are a hero! Certainly the saviour of my sanity.

    Just out of curiosity, is it possible to say in a few word what was going on? Over on github you mention character encoding issues. But how was that triggered by equation numbering?

    • CommentRowNumber30.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017

    Well the default library that Maruku was using for string scanning had the bug related to equation numbering. When I switched to a different string scanning library, this issue was fixed but then we started getting other errors on a lot of pages. The reason turned out to be that the second library wasn’t equipped to handle multibyte character sets like UTF-8. Once I figured out what was going on, it turned out to be easy to fix.

    • CommentRowNumber31.
    • CommentAuthorUrs
    • CommentTimeOct 11th 2017

    I see, interesting.

    By the way, is there a maximum length for anchor names (either for defs/props or for equations)?

    I like to use long explicit anchor names, but at some point I got worried that this is maybe causing some errors.

    • CommentRowNumber32.
    • CommentAuthoradeelkh
    • CommentTimeOct 11th 2017

    I’m not aware of any restriction on the length of anchor names, no.

    • CommentRowNumber33.
    • CommentAuthorMike Shulman
    • CommentTimeOct 11th 2017

    Still something wrong with the Unicode I think: at promonoidal category the RIGHTWARDS ARROW WITH VERTICAL STROKE characters ⇸ in the source show up on the page as three “Unknown character”s. Maybe a multibyte-ness problem?

    • CommentRowNumber34.
    • CommentAuthorUrs
    • CommentTimeOct 11th 2017
    • (edited Oct 11th 2017)

    Also, five minutes back when saving again in the Sandbox, the “500” error suddenly was back. Trying again, it works now.

    There was a similar time-dependency of the problem before. Is that somehow explained by the fix that you, Adeel, have made, or, otherwise, is it maybe an indication that there is a second, parallel, problem?

    • CommentRowNumber35.
    • CommentAuthoradeelkh
    • CommentTimeOct 12th 2017
    • (edited Oct 12th 2017)

    @33: I’m not sure that was caused by the latest changes. For example, using unicode in math commands doesn’t work here either:

    Unknown characterUnknown characterUnknown character

    and there haven’t been any changes to the nForum configuration. I would assume it’s just an iTeX issue. To be honest, I don’t even know whether this works in LaTeX. Of course in this instance it can be fixed by changing ⇸ to \twoheadrightarrow.

    • CommentRowNumber36.
    • CommentAuthoradeelkh
    • CommentTimeOct 12th 2017

    @34: It could be a completely separate issue. I would have to reproduce the bug in order to diagnose it, which I haven’t been able to do when I tried just now.

    • CommentRowNumber37.
    • CommentAuthorUrs
    • CommentTimeOct 12th 2017

    Sure, thanks. The moment I receive an error message from the server, I suppose in that moment some stack trace is written to the logs? Would it help if, next time, I try to give the precise time when the error occurs, so that it can be found in the logs?

    • CommentRowNumber38.
    • CommentAuthoradeelkh
    • CommentTimeOct 12th 2017

    That would help, yeah.

    • CommentRowNumber39.
    • CommentAuthorMike Shulman
    • CommentTimeOct 12th 2017

    Re #35, well it was caused by some change, because it used to work. For instance, you can see on my personal page that I recorded how to make barred arrows (which are not the same as two-headed arrows) and esh.

    (Unicode does work in math mode in LaTeX, as long as you import the right packages.)

    • CommentRowNumber40.
    • CommentAuthorMike Shulman
    • CommentTimeOct 12th 2017

    Oh, I think I see. Maybe unicode in math never used to work in iTeX, but what did (and still does) work is HTML character entities in math: $A &#8696; B$ gives ABA &#8696; B. What appears to have happened is that all the HTML character entities on nLab pages have been replaced by their actual unicode equivalent characters. This is worrisome, since it seems like it might be rather hard to globally undo.

    • CommentRowNumber41.
    • CommentAuthoradeelkh
    • CommentTime7 days ago

    Yeah, good catch.

    What appears to have happened is that all the HTML character entities on nLab pages have been replaced by their actual unicode equivalent characters.

    This is the inadvertent result of a script I ran to fix any encoding issues in all the pages. I made a backup we could restore to, but I’m not sure unicode characters instead of HTML entities is a bad thing. I’d rather fix the iTeX issue, which seems like it shouldn’t be much work.

    • CommentRowNumber42.
    • CommentAuthorMike Shulman
    • CommentTime4 days ago

    The conversion of &lt; to < has also broken the text of all the “history” pages. When a page A needs to be removed in a merge, we rename it to A > history and replace its content with &lt; [[B]] where B is the page that it was merged into; the latter displays as “< B” with a link. But now all the history pages contain < [[B]] instead, which does not display as anything, because iTeX parses it as the beginning of an HTML tag I guess.

    The instructions for this are at HowTo#merging. But actually those instructions are now also broken! Did backquotes get changed to forward quotes at the same time? Backquotes must be in lots of other places on the lab too.

    • CommentRowNumber43.
    • CommentAuthorUrs
    • CommentTime3 days ago
    • (edited 3 days ago)

    Maybe this is related: Now I get “Error 502: Bad Gateway” when asking for “latest changes” on the file, specifically when clicking on this link here:

    https://ncatlab.org/nlab/revision/diff/geometry+of+physics+–+A+first+idea+of+quantum+field+theory/45

    • CommentRowNumber44.
    • CommentAuthorMike Shulman
    • CommentTime3 days ago

    So do I.