Freeform: submit results in system error message without a message

Question

weird problem. I have a website with freeform that suddenly broke. When you submit a form a basic ExpressionEngine error message is shown but without an error message.

After discovering the problem i upgraded the system from ee2.3.1/freeform3.1.5 to ee2.6.0/freeform4.0.12 but the exact same problem keeps happening. I've already stipped down a test form to the bare minimal but that doesn't change anything.

{exp:freeform:form
    form_name="adwords"
    return="homepage/verzonden"
}
    <label>E-mail</label>
    <input type="text" name="email"/>
    <button type="submit">Verzenden</button>

{/exp:freeform:form}

Anybody got a clue where to look next?

Answer 1

The great people of solspace took a look at my systems and found the error.

It was caused by me using the Low NoSpam add-on. It was causing an error without outputting an error message. Disabling the add-on restored functionality.

Answer 2

So the big question is, What changed before it broke?" ,htaccess? new server? Are you getting any php errors? Any console errors? This is not an error I have seen before. Any chance I can get a CP login and ftp access to your site? support att solspace dott com