Upload File - Error 500

Hello,

As soon as I upload (via WordPress) a file larger than 500 Kb, I get a 500 error with Ngix
"500 Internal Server Error" or the following message "The server returned an unexpected response. However, the file may have been uploaded successfully. Please check the media library or refresh the page."
The file size limit to upload is set to 2GB, where can the problem come from?

Thanks for your help

My problem was solved by adding this parameter in the Varnish conf http_req_size: 64k