Have you checked the permission of the docroot?If there is a permission problem you can find an error inside the dispatcher.log.If there is this error you have to change permission of docroot in order to allow dispatcher to write in this folder.What you can do is to check the user that run the httpd...
Hi,this kind of error are verified when the HTML of the page is built with javascript call. It's your case? if yes, the workaround could be to use the template image instead of generate the thumbnail.
Have you put the translation of your keywords in dictionary? If yes, are you able to see the dictionary request in your browser? (Something like 'dict.en.json')
Have you already tried to change the Apache Sling Request Parameter Handling configuration?You can select like Default parameter encoding the UTF-8 instead of ISO.
If you try to open the url from the system console, you have a 404?something like: system/console/jmx/org.apache.jackrabbit.oak%3Aid%3D14%2Cname%3D%22repository+manager%22%2Ctype%3D%22RepositoryManagement%22