Problem with image file names containing utf-8 characters I have a problem image file names containing utf-8 characters in my drupal website. 
When drupal has to display a thumbnail (image style) that contains utf-8 characters on it's image file, it fails. All other images/image file names, work ok.

For example there's this image:

http://example.com/sites/default/files/styles/thumbnail/public/%CE%B8%CF%81%CE%B7%CF%83%CE%BA%CE%B5%CF%85%CF%84%CE%B9%CE%BA%CF%8C%CF%82%20_%CE%B3%CE%AC%CE%BC%CE%BF%CF%82.jpg

The actual image file really exists in default/files/styles/thumbnail/public/ directory, but it cannot be displayed in website. 

Visiting the above image url, I can see the following message:

Error generating image.

but I should be able to see the actual image, because it exists on server directory, I can download it using FTP, and it's a normal thumbnail image file.

Why is this happening and what can I do to fix it?

UPDATE-----

htaccess.txt

sample image
Use https://www.drupal.org/project/transliteration to automatically rename the files and avoiding problems like this. No need to train your editors. :-)