Error 0 after upgrade to J35

After upgrade to Joomla! 3.5.0, I get this message when accessing to the component in backend :

0 Could not connect to MySQL.
And same thing (0 error : 0 Could not connect to MySQL. message) in frontend after chronoforum item menu selected

I have the same problem with Chronoforms

PHP version : 5.6.19

for information :
Same thing on a new install of Joomla! 3.5.0 (local)
Same thing with Chronoforms (latest) too on this new install
Tried to install at random other components on this new install : all of them are working fine

Tried with a new install Joomla! 3.4.8 : same problem
Still PHP 5.6.19

Good luck... Looks like the developer abandoned the project....

Hi,

Using the ISIS3 Admin template as in this ChronoForms FAQ makes the Forum admin accessible when I test. The other template setting change will probably also work.

Bob