mb_convert_encoding(): Argument #3 ($from_encoding) contains invalid encoding "default"

with php 8 and vtiger 8 i have this error in mail manager: mb_convert_encoding(): Argument 3 ($from_encoding) contains invalid encoding "default"

To reproduce the error, just go to mail manager, if you see a blank page when listing 'received email', apply the following modification and check again.

The problem is fixed editing modules/Settings/MailConverter/handlers/MailRecord.php, search for function __convert_encoding after instruction if(!$from) $from = mb_detect_encoding($input); add the following if($from=='default') $from = mb_detect_encoding($input);