function.sprintf: Too few arguments in ….\updraftplus.php

Hi!

I’m running a scheduled backup with updraftplus 1.5.5 and I receive a this message:
Warning: sprintf() [function.sprintf]: Too few arguments in ……/wp-content/plugins/updraftplus/updraftplus.php on line 383

May you help me to fix iut?

TIA,
Manu

http://ww.wp.xz.cn/extend/plugins/updraftplus/