works locally but server says: Uncaught SyntaxError: Unexpected token N

[Jan Stanstrup]

I am working on an app where the user uploads a csv file, data is extracted and written to a mongodb and for testing the data is read back from the db and shown.

This works fine locally but on the server something happens after the data is read back from the db. The renderUI I am using seems to never be created and the console gives the following error:

1. Uncaught SyntaxError: Unexpected token N shiny.js:812
1. dispatchMessageshiny.js:812
2. socket.onmessageshiny.js:539
3. d.dispatchEventsockjs-0.3.min.js:27
4. y._dispatchMessagesockjs-0.3.min.js:27
5. y._didMessagesockjs-0.3.min.js:27
6. b.onmessagesockjs-0.3.min.js:27
7. d.dispatchEventsockjs-0.3.min.js:27
8. c.xo.onchunksockjs-0.3.min.js:27
9. f.emitsockjs-0.3.min.js:27
10. g.xhr.onreadystatechange

The app can be found here: https://github.com/stanstrup/shiny.apps/tree/master/apps/retdb and a sample input file has been attached.

Any idea what is going on?

I am using shiny package shiny_0.9.1.9015 and server shiny-server-1.1.0.10000-amd64 on ubuntu.

I tried to install the server from github but it appears that my apache redirection of port 3838 to a subfolder stopped working if I did that (other apps stopped working when using domain.com/shiny instead of domain.com:3838).

[Jan Stanstrup]

Example input file was malformed. Attached is a correct file.

[Yihui Xie]

This error message seems to indicate that the WebSocket could not
decode the message. From my experience, this means the message
probably contained multi-byte characters that were not appropriately
encoded, which could be a consequence of a locale bug that we recently
discovered and fixed in Shiny Server. If possible, please test a more
recent version of the Shiny Server:
https://s3.amazonaws.com/rstudio-shiny-server-os-build/ubuntu-12.04/x86_64/shiny-server-1.2.0.355-amd64.deb
Thanks!

Regards,
Yihui

[Jan Stanstrup]

Thank you for the reply. That version gives me some of the same symptoms as when I tried to compile from github. It seems that all items generated with renderUI/uiOutput are not displayed.

The console says:

WebSocket connection to 'ws://APP_PATH1/__sockjs__/102/pu8n9_sc/websocket' failed: Error during WebSocket handshake: Unexpected response code: 400
sockjs-0.3.min.js:27

But I got similar messages before that didn't seem to cause problems.

Another app I have cannot find some files with the new version:

GET http://APP_PATH2/css/styles.css 404 (Not Found) predret.com/:21

GET http://APP_PATH2/js/responsiveTable.js 404 (Not Found) predret.com/:22

I am wondering if something changed that is conflicting with my redirection of the shiny port to a dir. In my apache config I have:

<VirtualHost *:80>

DocumentRoot /var/www/html

  <Proxy *>

    Allow from localhost

  </Proxy>

ProxyPass        /shiny/ http://localhost:3838/

ProxyPassReverse /shiny/ http://localhost:3838/

RedirectMatch permanent ^/shiny$ /shiny/

</VirtualHost>

If I access the apps on the port directly it seems to work now. Any idea how to fix the redirection?

Jan.

[Joe Cheng]

If you're proxying through Apache then I think websocket failure is expected, and Shiny Server falls back to websocket emulation. Oh and looking at your original stack trace, indeed that's the case. Is the response code 400 the only error message that's showing up in the JavaScript console?

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[Jan Stanstrup]

Yes it is the only message.

[Jan Stanstrup]

Some googling suggest that apache now includes a mod_proxy_wstunnel that should be able to redirect the websocket. But so far I fail to understand how to use it for shiny.

Any ideas? But I don't know if that is even the problem as my apps worked with previous versions.

[Jan Stanstrup]

Any ideas how to figure out what is going on here? The "Uncaught SyntaxError: Unexpected token N" was solved by the latest version. But I cannot get renderUI/uiOutput to display with the new version but it works with the old version.

It definitely seem to have to do with the proxying. But should there be a difference with the new version? If so any hints about how to resolve it would be greatly appreciated.

[Fereshteh Karimeddini]

Jan,

Sorry for delayed response. I verified that the new version of Shiny Server has a problem with certain proxy setups. We are looking into the issue, and possible workarounds for it.

Thanks for reporting the problem,

Fereshteh

[Aurelien Tylski]

I've the same problem, i hope you'll fix it fast. Thanks a lot for your job, shiny is just amazing ! ;)

[Aurelien Tylski]

Well well well, i don't know if it gonna help you but i give you a little information. Because i'm french i use accent (à é ê è and some letter like ç) and in some language those characters are not avaible... If i remove all those in my db (postgresql, i use Rpostgresql package) and in my ui... Well i don't have the "Uncaught SyntaxError: Unexpected token N" error... You might think it's stupid or useless, anyway i give you this information hoping it'll help :) . So can it be a problem like Shiny is not using UTF8 ? Or something like this ?

Well now i have to write a function to block to my user the possibility to use those characters... :) ! Thank a lot for your work on Shiny ;) have a nice day

[Yihui Xie]

The next version of shiny, 0.10.1, will require multi-byte characters
to be encoded in UTF-8. Please see the announcement for beta testing
here: https://groups.google.com/forum/#!topic/shiny-discuss/kT4GAm_FAYU

Regards,
Yihui