When trying to install a theme from any of the 3 methods in the theme is not installed and you receive an error:

1. Import from your computer
   
2. Import from the web
   
3. Import from FTP - (Install from theme directory)
   

Cause

Files and folders are missing from the cache folder. This is most likely caused by people deleting all the files and folders in the cache folder because they think this is how to empty the cache and that everything in this folder can be deleted.

You will most likely see an error in (Advanced Parameters --> Configuration information) showing that there are files missing in the cache.

Solution

Follow the following steps to reconstruct the cache file and folder structure of Prestashop:

1. Download a fresh copy of Prestashop with the same version number as your shop
2. Extract all of the files and folders in the cache folder from the zip into the cache folder of your shop

Links

• [SOLVED] Error uploading product image - OUT - 1.6.0.11 [7 Jan 2015] - PrestaShop