Run clamscan with -ri option will cause it reporting only infected files and then always raise this error or warning message. Maybe try to change it to -r instead. (within plugins\ClamAV.php)
The -i switch is in there twice. A corrected line follows:
public $executable = array('Windows' => "%SA_HOME%resources\\utility\\clamav\\clamscan.exe --no-summary -d
%SA_HOME%resources\\utility\\clamav\\ -r --detect-pua --no-mail --max-recursion=5 --max-dir-recursion=30 ",
'Linux' => "clamscan --no-summary -r --detect-pua --no-mail --max-recursion=5 --max-dir-recursion=30 ");
Thank you - this will be fixed in v2.1 which will be released very soon!
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