Should I be concerned if my website throws stack information?

I have a simple login form on my web page and the URL looks like this:

http://ift.tt/1GkhKfa

If I try something like this:

http://ift.tt/1BlRDPs

I'm redirected to a stack dump that looks something like this:

exception 'DOMException' with message 'Invalid Character Error' in /<mydirectory>/a_xml.class.php:74
Stack trace:
#0 /<mydirectoy>/a_xml.class.php(74): DOMDocument->createElement('()')
...
#6 {main}

Is this a big problem in terms of security? Are there any attacks a malicious user can perform that will allow him to deface or steal my database? Or is this relatively benign and I can ignore it?