[PROBLEM] Cant Download From Forum

i hav a problem, recently i install jcms v4.2.0 , all thing works fine bt i cant dwnload attachment, when i click to dwnload thn comes a blank white page...
here is my error_log file
plz help anyone

Most likely you have edited the file forum / includes / file.php and made ​​a mistake in it.
Replace the original file from the distribution.