Got a new display on my FP2 and installed the last ported version of Sailfish OS (2.1.3.7) again.
(Great OS on a great device!!) Everything runs smooth except one issue:
Everytime I search for Bluetooth devices, the phone reboots.
In Fairphone Open OS 18.02 it worked normally.
I read about the same problem in an older SFOS release, but I couldn’t find any solutions.
The Bluetooth related reboots are caused by issue with recent modem partition and Sailfish needs older firmware, the installation instructions tell users to flash the older modem partition. In your case you probably forgot to fastboot flash the modem partition from the Fairphone OS 1.5.1 as mentioned here https://wiki.merproject.org/wiki/Adaptations/libhybris/Install_SailfishOS_for_fp2#Installation_steps.