Upgrade Error, Fatal error: Call to a member function setAttribute()
I am upgrading from C5 version 188.8.131.52 to 5.6.0 but after clicking on the 'Upgrade' button it loads for about 5 seconds and then displays; Fatal error: Call to a member function setAttribute() on a non-object in [site-path]/concrete/core/models/collection.php on line 239.
I have the following add-ons installed;
* Gallery Banner - 1.5
* PHP block by ND - 1.0
* tnSpacer - 1.3
I did have the add-ons 'Sortable Fancybox Gallery' and 'Blogga' but have uninstalled these and removed there delated db tables but still no success.
I have a feeling it may be the user permissions but not 100% sure, any help on this subject would be a life saver :)