CPANEL-38154 - Error when saving file in File Manager. Request is too long (length is 94211, maximum length is 65535)

Hi, I have a client who's having a problem to save file (edited using File Manager), but received the below error : ERROR Failed to parse adminbin request: Request is too long (length is 94211, maximum length is 65535) at /usr/local/cpanel/Cpanel/AdminBin/Server.pm line 162. I have tried disabling 'mod_security' & Immunify360, and updated cPanel version to 100.0.9., but to no avail. I have searched this topic in this forum, but found nothing. Your help is appreciated.