smush pro Error posting to API: 500 Internal Server Error

Hi,

Can you tell me or explain me or even fix the errors when I want to Bulk smush my new image
Smush individual images via your Media Library
0/6 images were successfully compressed, 6 encountered issues.

welcomepakage8.png
Error posting to API: 500 Internal Server Error
welcomepakage7.png
Error posting to API: 500 Internal Server Error
welcomepakage6.png
Error posting to API: 500 Internal Server Error
Welcomepackage5.png
Error posting to API: 500 Internal Server Error
welcomepakage4-1.png
Error posting to API: 500 Internal Server Error

Maybe I have a plugin that it's not compatible with my theme ?!
Thanks for your help.
Sylvie