Hello,
1) You have used nulled version of our theme https://prnt.sc/has47t and now you won’t be able to use autoupdate option for theme or included plugins because of changes that you made when installing nulled theme. We also can’t guarantee 100% correct work of our theme if you used nulled version.
2) We don’t have another answer from Massive Addons author about this issue http://prntscr.com/hasa7c except this one:
make sure that your server is not using mod_security or FastCGI handler for PHP. If it is, you need to contact with your hosting provide and ask to increase the maximum body length value.
and this one http://prntscr.com/hasdof
And if you check the topic you’ll see that it should help http://prntscr.com/hasbdn
Or you may contact plugin author, maybe he will find another solution for you.
Regards