Fix can't enable Front-end Builder in admin ( Migrate from M1 to M2 )
+ Disable MGS_Mpanel module by going to your server, access to app/etc/ and edit file config.php then change 1 -> 0 with MGS_Mpanel module
+ Go to database edit setup_module table then find a record with MGS_Mpanel of Module field and delete it
+ Connect to ssh, navigate to magento root then run:
+ php bin/magento module:enable MGS_Mpanel
+ php bin/magento setup:upgrade
+ php bin/magento setup:static-content:deploy -f