Enabling exif extension for PHP.

If you are on Windows, edit your php.ini file and uncomment these two lines:

extension=php_mbstring.dll
extension=php_exif.dll 

make sure the order of the extensions are same as above ( exif depends on mbstring and hence mbstring should be loaded first).

If you are on Ubuntu, run the following command:

ls `php -i | grep "^extension_dir" | sed -e 's/.*=> //'`

This will display a list of all the installed extensions in your system. Check if exif.so and mbstring.so are present in the list. If you do not spot these two extensions listed, you can install them easily:

sudo apt-get install php7.0-mbstring && sudo apt-get install php7.0-common

Hope this helps.