Notes: HTTP 500 error in Dashboard

[Valdnet]

After entering Dashboard, I get an HTTP 500 error.

Server (please complete the following information):

• Notes app version: 4.0.0
• Nextcloud version: 20.0.0
• PHP version: 7.3.16

Log files
Add relevant parts of your nextcloud.log and/or your browser's JavaScript console here.

Exception: 

    /home/xxx/public_html/cloud/lib/private/AppFramework/Http/Dispatcher.php - line 123:

    OCP\AppFramework\Http\JSONResponse->render()

    /home/xxx/public_html/cloud/lib/private/AppFramework/App.php - line 152:

    OC\AppFramework\Http\Dispatcher->dispatch(OCA\Notes\Co ... {}, "dashboard")

    /home/xxx/public_html/cloud/lib/private/Route/Router.php - line 308:

    OC\AppFramework\App::main("OCA\\Notes\ ... r", "dashboard", OC\AppFramew ... {}, { action: nu ... "})

    /home/xxx/public_html/cloud/lib/base.php - line 1009:

    OC\Route\Router->match("/apps/notes/notes/dashboard")

    /home/xxx/public_html/cloud/index.php - line 37:

    OC::handleRequest()

[korelstar]

Hmm, honestly I have no idea which could cause this exception. The log excerpt is not very meaningful. :-(

Could you please try to restart your webserver and php-fpm (if used)? Sometimes this helps with strange issues.

Does the notes app itself work?

Does anybody else have such a problem?

[Santobert]

Does anybody else have such a problem?

I have this issue as well. Latest Nextcloud in Docker with nginx reverse proxy. Nothing special besides that.

As far as I can see, the notes app itself works as expected. It's only the dashboard that's not working.

[Valdnet]

Does the notes app itself work?

The application is working fine.

[korelstar]

I tried to reproduce this issue with docker, but I failed. Can you please provide more information about your setup? A step-by-step guide on how to setup the problematic environment would be nice.

Are there any special notes in your account? Does this happen to every account on that server?

Maybe somebody can find a more meaningful log with an exception message and without shortened strings?

[Santobert]

The error doesn't show up in the docker logs.

There are some JS Errors:

Uncaught TypeError: OCA.Files.DetailTabView is undefined
    <anonymous> [url]
    <anonymous> [url]
activity-sidebar.js:603:24

Uncaught TypeError: n.Files.DetailTabView is undefined
    <anonymous> commentstabview.js:21
    <anonymous> commentstabview.js:756
    Webpack 3
commentstabview.js:21:23

Uncaught TypeError: OCA.Files.DetailTabView is undefined
    <anonymous> versionstabview.js:18
    Webpack 3
versionstabview.js:18:7

Error: Request failed with status code 500
    exports createError.js:16
    exports settle.js:17
    onreadystatechange xhr.js:69
NotesService.js:55:11
    A NotesService.js:55

Uncaught (in promise) Error: Request failed with status code 500
    exports createError.js:16
    exports settle.js:17
    onreadystatechange xhr.js:69
createError.js:16:14

And there is another error, that shows up in the server logs:

[index] Error: Exception: null at <<closure>>

0. /var/www/html/lib/private/AppFramework/Http/Dispatcher.php line 123
   OCP\AppFramework\Http\JSONResponse->render()
1. /var/www/html/lib/private/AppFramework/App.php line 152
   OC\AppFramework\Http\Dispatcher->dispatch(OCA\Notes\Controller\NotesController {}, "dashboard")
2. /var/www/html/lib/private/Route/Router.php line 308
   OC\AppFramework\App::main("OCA\\Notes\\Controller\\NotesController", "dashboard", OC\AppFramework\ ... {}, {action: null,_r ... "})
3. /var/www/html/lib/base.php line 1009
   OC\Route\Router->match("/apps/notes/notes/dashboard")
4. /var/www/html/index.php line 37
   OC::handleRequest()

GET /apps/notes/notes/dashboard
from [ip] by [user] at 2020-10-26T06:42:58+00:00

I hope this helps, since I can't provide a detailed step-by-step guide how to reproduce this error.

[Santobert]

It looks like this issue is listed twice: https://github.com/nextcloud/server/issues/23241

[korelstar]

Thanks, but I'm still not sure what's the problem's source. It could be something related to the notes character set, because JSON rendering seems to fail. But I still wasn't able to reproduce. Therefore, please answer some more questions:

• does this happen even if you have no notes in your account? (for testing purposes you could temporarily change the notes path to an empty folder)
• what language have your notes / do the notes contain some/many (?) multi-byte/non-ASCII characters?
• does the issue happen for anybody in a non-Docker setup?

[Santobert]

Wow that's it. Some of my notes contained square meters (²). After I had removed the small 2, the error was gone.

[D-side]

I haven't had a more elusive yet stable issue in quite a while.

This issue occurs when 100 bytes past the start of the note is inside a UTF-8 multibyte character. E. g. if a note is comprised of 99 single-bytes and 100th multibyte. This is very easy to hit in Russian, since it uses a Cyrillic charset (2 bytes per UTF-8 char), but spaces and punctuation from ASCII (1 byte each). But since the condition is so obscure, some texts work and some don't seemingly at random (except not!).

Create a note with this text to reproduce the issue (and make sure to set the title to something different):

So if I provide a sufficient amount of English text to invoke truncation, does anything nasty occur¿

And that seems to be because excerpt generation uses substr which for multi-byte encodings may stop mid-character, producing invalid UTF-8 which causes some breakage inside. I don't know my way around PHP very well, but it sounds like using mb_substr + "utf-8" instead may fix this.

https://github.com/nextcloud/notes/blob/937c08754bdd984a0a8eb85b0bb9b0008f004586/lib/Service/Note.php#L57-L71

[bentolor]

Thanks, @D-side !

I can confirm this is the issue & fixes it, @korelstar ! I'm a german user and had this issue for quite some time. With the hint of D-side I just went inside the docker container an hot-patched the given lines by simply replacing the two substr instances with mb_substr calls. and it immediately started to work.

I'm a total PHP noob and not sure to the full extent about the "100" and the strange magic codes appended. If it helps I can provide a MR with the change.

[bentolor]

On looking on the PHP API documentation it seems by first modification is wrong and I should use $excerpt = mb_substr($excerpt, $length, NULL, "utf-8"); instead. (Not sure: Does PHP sth. like named arguments?)

I created a pull request https://github.com/nextcloud/notes/pull/630 for everybodies convenience