Upload error on Classipress Theme

Hi,
I have installed your plugin for frontend users can upload her avatar but when I try to upload the file (300×400 27kb) but when I click on upload I have this error:
File is empty. Please upload something more substantial. This error could also be caused by uploads being disabled in your php.ini or by post_max_size being defined as smaller than upload_max_filesize in php.ini.

I tryed with Administrator user and normal user on frontend but same error.
I have only installed your plugin (1.5.1) and enable the Anyone can upload but it not work.

I need to change or set something?

Thanks

https://ww.wp.xz.cn/plugins/avatar-manager/