@all:
When you get this error message:
0 - Call to undefined method JDHelper::existsCustomFieldsTitles()Please note that this function is not more a part from version 3.9.x. It exist only in the old 3.2.x series.
You should check your override html folder.
Then the error could be the result from older files which you had prior change with the override function in Joomla.
In the new version 3.9.6 (comes later today) we have added a few checks so that the user in this case get a special hint.
