After a clean openMRS installation and while adding some patients and some concepts and every thing was fine. Now when I try to add new concept I get an error message with no text in it, I noticed also that I am not able to add attachment to the pt visit the upload bar appears then nothing happens (that was ok).
here is my sever logs since the problem: https://pastebin.com/ZWcCA2w7
Sorry for so many questions, but this is my first successful openMRS implementation after so many trials. Thanks in advance