white page after update joomla 3.4.7

hello, sorry for my bad english (I'm french)
After a joomla's 3.4.7 update, I have a white page where my form is
Have anyone this problem ? Thanks for answer

Après une mise à jour de joomla 3.4.7, j'ai une page blanche à l'endroit où se trouvent les formulaires. Quelqu'un d'autre aurait également eu ce problème ?
Merci de vos réponses

Hi, make sure you have click the "clean cache" button in the Joomla Update component. You can reach this component when you click the "Joomla! is up to date link" in the control panel of your website.

Regards,
Aicha

thanks for the quick response !
but I have already tried this. Another idea ?
I haven't link because I'm in local machine

enable debug system and set error reporting to developer in global configuration. Maybe you will get an error message in frontend then.

debug system does'nt appear where the form is...
In back office, I can't clic in the field, it's locked and I can't unlock it
When I remove all fields, I can see the title and copyright of the form

Sorry, at the moment I have no further ideas. I have updated all my websites to 3.4.7 without problems. I think this is a specific problem of your Joomla! installation on your local XAMPP.

Regards,
Aicha