Error message

Warning: readfile(https://poc.solverlabs.com/sites/default/files/Screenshot_2018-05-29-15-44-22%5B1%5D.png): failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found in poc_common_download_file() (line 426 of sites/all/modules/custom/poc_common/poc_common.module).