install/update/new/language/en/install.php:463
'NUMBER_OF_FILES_COLLECTED' => 'Currently having differences about %1$d from %2$d files collected.<br />Please wait until file collection finished.',

To me this string made no sense. I suggest it be changed to something like

'Currently differences of %1$d of %2$d files have been collected.<br />Please wait until all files are checked'