Unable to generate the derived image Today I uploaded my site to the server, and I get errors like the following:


  Unable to generate the derived image located at public://styles/sponsor_image/public/TerraThermaSponsorLogo.png.


Image styles cannot generate images. I have tried to set permissions on styles/* folders with chmod -R 775 styles/, and even tried chmod -R 777 styles/. The folder's owner is OK. I don't get what can be wrong.

The directory associated with public:// is sites/default/files, and it is OK.
You should also make sure you do have a graphical library (like php-gd) installed on your server: check /admin/config/media/image-toolkit (D7).