Fortigate config 200E vs 200F

Greetings, just got some new 200Fs and tried loading a base config from one of our 200E series FGTs. Interestingly enough it made 200F unusable to a point where I had to reformat boot partition and reload FortiOS from TFTP server. My usual deployment process with E-series models is to load a base config with modified for a specific site FGT name and MGMT port IP, authorize new FGT in FMG and then continue with the rest of the new FGT settings in FMG. Could someone tell if this would still be doable without paying for FortiConverter service and what should be added/removed/modified on 200E config to make it work with our new 200Fs? Thanks