hello,
the problem is at wpdm-functions.php:l311.
there is no ob_start() in the first place, so you’ll get an error:
“PHP message: PHP Notice: ob_flush(): failed to flush buffer. No buffer to flush in …plugins/download-manager/wpdm-functions.php on line 311
I think the ob_flush is unnecessary, but you can insert before L305 a “ob_start()” or suppress the ob_flush error with @ob_flush.
After all i would simply delete the ob_flush()