After upgrading from 2.1.5 to 2.1.6 CE. I'm getting below error on Windows WAMP while saving product on Admin side.
Unable to write file into directory
\D:/wamp/www/magento/pub/media/catalog/product\cache\3cf5799449660ed39031217945ace72a/H/3.
Access forbidden.
I tried below but it's for Linux
Access Denied (Permission Issue) after upgrade 2.0.3 -> 2.0.4
Best Answer
I just updated to Magento 2.1.6 on Windows and had this same issue. I did a little searching and came across a post on Github here.
In a nutshell you need to do two things in vendor/magento/module-catalog/Model/View/Asset/Image.php.
The first thing is replace all occurrences of DIRECTORY_SEPARATOR with '/'
The second is edit the getRelativePath function to look like:
You need both changes or it won't work. Just replacing DIRECTORY_SEPARATOR still throws a forbidden error. Not including the $prefix elements in getRelativePath causes the forbidden error to go away, but product images won't load.