Error code -1073741515

Getting the following from a client when it tries to backup. How can I fix this?

UrBackup just did a full file backup of “computer”.

( 1 info, 0 warnings, 2 errors )

2017-04-11 23:23:18(info): Starting scheduled full file backup…
2017-04-11 23:23:18(error): Constructing of filelist of “computer” failed: error - prefilebackup script failed with error code -1073741515
2017-04-11 23:23:28(error): Backup had an early error. Deleting partial backup.