Comment form missing XID - Form submits but data doesn't save

Question

As noted, the form submits but the data doesn't go into the db. Looking at the rendered HTML, I notice a missing XID. I think this is what is causing the problem - anyone know why this would happen?

{exp:comment:form channel="articles" entry_id="{embed:entry_id}"}

    {if logged_out}
            <label for="name">Name:</label><input type="text" name="name" value="{name}" size="50" /><br />
            <label for="email">Email:</label> <input type="text" name="email" value="{email}" size="50" /><br />
    {/if}

    <label for="comment">Comment:</label>
    <textarea name="comment" cols="70" rows="10">{comment}</textarea>
    <label><input type="checkbox" name="save_info" value="yes" {save_info} /> Remember my personal information</label>
    <br />
    {if captcha}
            <label for="captcha">Please enter the word you see in the image below:</label><br />
            <p class="captcha">{captcha}<input type="text" name="captcha" value="{captcha_word}" maxlength="20" style="width: 200px; float: left;" /></p>
    {/if}
    <br />
    <input type="submit" name="submit" value="Submit" />

{/exp:comment:form}

Source:

<form id="comment_form" method="post" action="http://domain.com/newsroom_article/core-to-corporate">
        <div class="hiddenFields" style="display: none;">
        <input type="hidden" name="ACT" value="29">
        <input type="hidden" name="RET" value="http://domain.com/newsroom_article/core-to-corporate">
        <input type="hidden" name="URI" value="newsroom_article/core-to-corporate">
        <input type="hidden" name="PRV" value="">
        <input type="hidden" name="XID" value="">
        <input type="hidden" name="entry_id" value="3327">
        <input type="hidden" name="site_id" value="1">
        </div>
        <label for="name">Name:</label><input type="text" name="name" value="" size="50"><br>
        <label for="email">Email:</label> <input type="text" name="email" value="" size="50"><br>

        <label for="comment">Comment:</label>
        <textarea name="comment" cols="70" rows="10"></textarea>
        <label><input type="checkbox" name="save_info" value="yes"> Remember my personal information</label>
        <!--                                                    <label><input type="checkbox" name="notify_me" value="yes"  /> Notify me of follow-up comments?</label> -->
        <br>
        <label for="captcha">Please enter the word you see in the image below:</label><br>
        <p class="captcha"><img src="http://domain.com/images/captchas/1354086872.7556.jpg" width="140" height="30" style="border:0;" alt=" "><input type="text" name="captcha" value="" maxlength="20" style="width: 200px; float: left;"></p>
        <br>
        <input type="submit" name="submit" value="Submit">
        </form>

Answer 1

Generally if form submissions aren't working, your .htaccess file is to blame.

Specifically, if you are using NSM htaccess generator, I've seen numerous problems with that, so avoid it. Also, if you are trying to force trailing slashes, stop now. EE 2.x really likes no trailing slash, and fighting it gets you nowhere.

The best solution is always to use the official htaccess, and nothing else:

RewriteEngine On

# Removes index.php from ExpressionEngine URLs
RewriteCond $1 !\.(gif|jpe?g|png)$ [NC]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /index.php/$1 [L]

Answer 2

If secure forms is set to no in security settings, EE's forms don't use XID. Whilst this doesn't solve the problem of the data not saving, it should explain why there is no XID...