What does this mean?
Nov 28 11:25:44 FPP-MASTER fppd_boot_pre[3120]: Running pre-start scripts
Nov 28 11:25:44 FPP-MASTER fppd_boot_pre[3120]: FPP - Turning OFF screen
blanking
Nov 28 11:25:45 FPP-MASTER fppd[3147]: terminate called after throwing an
instance of 'Json::LogicError'
Nov 28 11:25:45 FPP-MASTER fppd[3147]: what(): Value is not convertible to
Int.
Nov 28 11:25:45 FPP-MASTER fppd[3147]: Magick: abort due to signal 6 (SIGABRT)
"Abort"...
Nov 28 11:25:45 FPP-MASTER systemd[1]: fppd.service: Main process exited,
code=killed, status=6/ABRT
I would try installing a new SD card with a new image. A failing SD card can cause errors like this because the Pi is no longer reading the software correctly.
It might be just a single config file is corrupt. You could also try bumping up the debug logging to 'Debug' for every category and restarting and then checking the fppd.log to see if it helps identify what fppd was doing at the time.