Hi all!
Here is the solution: http://forum.joomla.org/viewtopic.php?f=710&t=800583#p3167456 It works with Joomla 3.6.0 and 3.6.1
I copy/paste from the url above:
Open your db with phpmyadmin or other app (#__ is your prefix table).
1 -Find the table #__content_types, see if you have any rows on it. If not, must insert the text in the attached file "fix_sql_tables_for_tags.txt" (unzip first)
2 -Find your table #__tags, must have at least 1 row for ROOT value, if not insert this:
CODE: SELECT ALL INSERT INTO #__tags
(id
, parent_id
, lft
, rgt
, level
, path
, title
, alias
, note
, description
, published
, checked_out
, checked_out_time
, access
, params
, metadesc
, metakey
, metadata
, created_user_id
, created_time
,created_by_alias
, modified_user_id
, modified_time
, images
, urls
, hits
, language
, version
) VALUES (1, 0, 0, 1, 0, ”, ‘ROOT’, ‘root’, ”, ”, 1, 0, ‘0000-00-00 00:00:00’, 1, ‘{}’, ”, ”, ”, ”, ‘2011-01-01 00:00:01’,”, 0, ‘0000-00-00 00:00:00’, ”, ”, 0, ‘*’, 1);
Again, don’t forget to replace #__ in the queries
I hope this helps Thanks L.