Undefined variable: user_links in include()

I have a same problem. Don't know how and where $user_links should be defined and have fixed the problem by assigning to the variable a blank value.

Add $user_links= "" in page.tpl.php like this:

$user_links= ""

Setting a value to 'nothing' that you don't know where it's used for doesn't sound like a good idea to me.

Before adding new issues you should search if the issue is already posted, this looks like the same as this issue:
#1165790: Notice: Undefined variable
And it's already solved.
So I'm marking this one as duplicate issue.

The solution basically is:
open a text editor, open urban_project/templates/page.tpl.php
search for
if ($user_links)
and change it to
if (isset($user_links))

Or wait untill this theme's creator (brentbice) commits it, so you can redownload the theme.

Ongoing work of this issue is in #1193374: Error message for drupal 7

The easiest workaround is to simply create a primary link on your menu to a page of yours. If you have none you'll see the error discovered.