That's a filesystem error.
Backtrace:
db:0:kdb.enter.default> bt Tracing pid 17 tid 100143 td 0xfffffe00513cc1e0 kdb_enter() at kdb_enter+0x32/frame 0xfffffe005187ca60 vpanic() at vpanic+0x163/frame 0xfffffe005187cb90 panic() at panic+0x43/frame 0xfffffe005187cbf0 ffs_blkfree_cg() at ffs_blkfree_cg+0x67b/frame 0xfffffe005187cca0 ffs_blkfree() at ffs_blkfree+0xa9/frame 0xfffffe005187cd00 freework_freeblock() at freework_freeblock+0x62d/frame 0xfffffe005187cd80 handle_workitem_freeblocks() at handle_workitem_freeblocks+0x168/frame 0xfffffe005187cde0 process_worklist_item() at process_worklist_item+0x24c/frame 0xfffffe005187ce60 softdep_process_worklist() at softdep_process_worklist+0xed/frame 0xfffffe005187ceb0 softdep_flush() at softdep_flush+0x11f/frame 0xfffffe005187cef0 fork_exit() at fork_exit+0x7f/frame 0xfffffe005187cf30 fork_trampoline() at fork_trampoline+0xe/frame 0xfffffe005187cf30 --- trap 0, rip = 0, rsp = 0, rbp = 0 ---The first thing to do here is run a manual filesystem check:
https://docs.netgate.com/pfsense/en/latest/troubleshooting/filesystem-check.html#manual-filesystem-check