This problem seems to have been fixed after I created a file named .htaccess with the following content and put it under mod/lesson directory.
<ifmodule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</ifmodule>
This problem seems to have been fixed after I created a file named .htaccess with the following content and put it under mod/lesson directory.
<ifmodule mod_security.c>
SecFilterEngine Off
SecFilterScanPOST Off
</ifmodule>