After an upgrade from 3.2.7 to 3.4.4 (build 20180720) successfully, we got this error when trying to access a resource file (m4a sound file) which was working on our previous version of 3.2.7.
We are running RHEL 7, PHP 7.1, and MySQL 5.7.x
The file is there as I can download it when editing it.
More information about this error
Error code: filenotfound
line 482 of /lib/setuplib.php: moodle_exception thrown
line 1913 of /lib/filelib.php: call to print_error()
line 4772 of /lib/filelib.php: call to send_file_not_found()
line 40 of /pluginfile.php: call to file_pluginfile()