It seems that your database can't set up the foreign key constraint for some reason. The correct path would be to review your data and make sure it is correct. In other words, the SQL must work, if it doesn't there is some inconsistency in your FAQ table. As an extreme case you can eliminate the constraint, the program will work the same and you will have custom field support on the FAQ module, simply the information in those custom fields will not be deleted when you eliminate a FAQ. Here is the change:

 

diff --git a/build/changeSets/cffaq.php b/build/changeSets/cffaq.php
index 3a10292..cf4896a 100644
--- a/build/changeSets/cffaq.php
+++ b/build/changeSets/cffaq.php
@@ -23,8 +23,7 @@ class cffaq extends cbupdaterWorker {
                } else {
                        $this->ExecuteQuery("CREATE TABLE IF NOT EXISTS vtiger_faqcf (
                                                faqid int(19),
-                                               PRIMARY KEY (faqid),
-                                               CONSTRAINT fk_1_vtiger_faqcf FOREIGN KEY (faqid) REFERENCES vtiger_faq(id) ON DELETE CASCADE
+                                               PRIMARY KEY (faqid)
                                                ) ENGINE=InnoDB DEFAULT CHARSET=utf8", array());
                        $this->sendMsg('Changeset '.get_class($this).' applied!');
                        $this->markApplied();