Strange bug on web hosted installation when posting a message [fixed]

Averell

I have three flarum forums installed on different web sites.
I found that when I type in a message :

first line
"second line"

I get the error : Oops! Something went wrong. Please reload the page and try again.
And the debug link shows only a disappointing message :

418 Unknown
POST http://forum.acsemb.org/api/discussions
null

This happens when I type a line, end of line, and the following line starts with "
Just add a space before " and no problem.

On the forum here, no problem.
On the local installations of these forums, no problem (these local installations share the same database with the web hosted installations, so problem is not in the database).

I tried to disable the two extensions I have added, configure-smtp and hyn-guardian. No change.
I tried to disable markdown and bbcodes. No change.

Any idea of what I can test ?

jordanjay29

Is your debug = true in your config.php?

Averell

jordanjay29 Yes, it is, and in many previous circumstances I had long debug messages. But sometimes it happens like that and debugging is difficult. Perhaps there is an error message in the Apache log but I don't have access to it on the website.
Writing this gives me an idea. The problem may be related to the Apache installation on the websites, since they are all hosted by Online.net. These installations have been made independently. So having the same bug on all of them makes me suspicious. But what can be the problem ? No idea. Is it possible to log the POST commands somewhere ?

Averell

It may come from mod_security (an Apache module).
Offending code is :

<br/>\n"

<br/> followed by a 0A code followed by a double quote.
I am trying to find where I would be able to replace this sequence, adding a space before the quotes, with something like :

 data.replace( '<br/>\n\"' , '<br/>\n \"')

But I have not yet found the place to do that.

Kulga

Averell It may come from mod_security (an Apache module).

Does disabling this module (temporarily) resolve the problem?

Averell

Kulga Does disabling this module (temporarily) resolve the problem?

Since this happens only on a hosted system, I don't have access to httpd.conf file

Averell

OK, I found the trick (just a dirty workaround) :

in flarum\vendor\flarum\core\js\forum\dist\app.js
on line 26700, I added :

.replace(/\n"/g, '\n "')

In context :

 key: 'data',
          value: function data() {
            return {
              content: this.content().replace('/\n"/g, '\n "'),
              relationships: { discussion: this.props.discussion }
            };

it adds a space before the " when it is placed in the beginning of a line.

The source of this code is in :
flarum\vendor\flarum\core\js\forum\src\components\ReplyComposer.js

Kulga

Marking as solved - but it seems like a unique situation to a specific host on a specific version of mod_security 😉
Considering the level of debugging you went through, I might suggest using a VPS!

Averell

Host provider suggests to test other versions of PHP. Does Flarum support 7.0 ?

jordanjay29

Averell Not yet.