diff --git a/lib/conditionlib.php b/lib/conditionlib.php
index 71d36c72110..2106d0e2cff 100644
--- a/lib/conditionlib.php
+++ b/lib/conditionlib.php
@@ -613,7 +613,6 @@ abstract class condition_info_base {
             'email' => get_user_field_name('email'),
             'city' => get_user_field_name('city'),
             'country' => get_user_field_name('country'),
-            'interests' => get_user_field_name('interests'),
             'url' => get_user_field_name('url'),
             'icq' => get_user_field_name('icq'),
             'skype' => get_user_field_name('skype'),
@@ -1252,7 +1251,7 @@ abstract class condition_info_base {
      * @param int $fieldid the user profile field id
      * @return string the user value, or false if user does not have a user field value yet
      */
-    private function get_cached_user_profile_field($userid, $fieldid) {
+    protected function get_cached_user_profile_field($userid, $fieldid) {
         global $USER, $DB, $CFG;
 
         if ($userid === 0) {
diff --git a/lib/db/upgrade.php b/lib/db/upgrade.php
index e82d141edc9..1dfad362861 100644
--- a/lib/db/upgrade.php
+++ b/lib/db/upgrade.php
@@ -1600,5 +1600,15 @@ function xmldb_main_upgrade($oldversion) {
         upgrade_main_savepoint(true, 2012120301.11);
     }
 
+    if ($oldversion < 2012120301.13) {
+        // Delete entries regarding invalid 'idnumber' option which breaks course.
+        $DB->delete_records('course_sections_avail_fields', array('userfield' => 'idnumber'));
+        $DB->delete_records('course_modules_avail_fields', array('userfield' => 'idnumber'));
+        // Clear course cache (will be rebuilt on first visit) in case of changes to these.
+        rebuild_course_cache(0, true);
+
+        upgrade_main_savepoint(true, 2012120301.13);
+    }
+
     return true;
 }
diff --git a/lib/tests/conditionlib_test.php b/lib/tests/conditionlib_test.php
index 75fed3cf3d2..180de296c2e 100644
--- a/lib/tests/conditionlib_test.php
+++ b/lib/tests/conditionlib_test.php
@@ -735,5 +735,56 @@ class conditionlib_testcase extends advanced_testcase {
         $this->assertFalse($ci->is_available($text, false, $USER->id + 1));
         $this->assertFalse($ci->is_available($text, true, $USER->id + 1));
     }
+
+    /**
+     * Tests user fields to ensure that the list of provided fields includes only
+     * fields which the equivalent function can be used to obtain the value of.
+     */
+    public function test_condition_user_fields() {
+        global $CFG, $DB, $USER;
+
+        // Set up basic data.
+        $courseid = $this->make_course();
+        $cmid = $this->make_course_module($courseid);
+        $ci = new condition_info_testwrapper(
+                (object)array('id' => $cmid), CONDITION_MISSING_EVERYTHING);
+
+        // Add a custom user profile field. Unfortunately there is no back-end
+        // API for adding profile fields without having an actual form and doing
+        // redirects and stuff! These are the default text field parameters.
+        require_once($CFG->dirroot . '/user/profile/lib.php');
+        $field = (object)array(
+                'shortname' => 'myfield', 'name' => 'My field', 'required' => 0,
+                'locked' => 0, 'forceunique' => 0, 'signup' => 0,
+                'visible' => PROFILE_VISIBLE_ALL,
+                'datatype' => 'text', 'description' => 'A field of mine',
+                'descriptionformat' => FORMAT_HTML, 'defaultdata' => '',
+                'defaultdataformat' => FORMAT_HTML, 'param1' => 30, 'param2' => 2048,
+                'param3' => 0, 'param4' => '', 'param5' => '');
+        $customfieldid = $DB->insert_record('user_info_field', $field);
+
+        // Get list of condition user fields.
+        $fields = condition_info::get_condition_user_fields();
+
+        // Check custom field is included.
+        $this->assertEquals('My field', $fields[$customfieldid]);
+
+        // For all other fields, check it actually works to get data from them.
+        foreach ($fields as $fieldid => $name) {
+            // Not checking the result, just that it's possible to get it
+            // without error.
+            $ci->get_cached_user_profile_field($USER->id, $fieldid);
+        }
+    }
 }
 
+
+/**
+ * Test wrapper used only to make protected functions public so they can be
+ * tested.
+ */
+class condition_info_testwrapper extends condition_info {
+    public function get_cached_user_profile_field($userid, $fieldid) {
+        return parent::get_cached_user_profile_field($userid, $fieldid);
+    }
+}
diff --git a/version.php b/version.php
index b43f0f56c42..0d2be17a728 100644
--- a/version.php
+++ b/version.php
@@ -30,7 +30,7 @@
 defined('MOODLE_INTERNAL') || die();
 
 
-$version  = 2012120301.12;              // 20121203      = branching date YYYYMMDD - do not modify!
+$version  = 2012120301.13;              // 20121203      = branching date YYYYMMDD - do not modify!
                                         //         RR    = release increments - 00 in DEV branches
                                         //           .XX = incremental changes