(gdb) bt
#0  __wt_txn_resolve_prepared_op (commit=true, op=0x7f7bb6657340, session=0x7f7baaf9c8e0) at src/third_party/wiredtiger/src/include/txn.i:214
#1  __wt_txn_commit (session=session@entry=0x7f7baaf9c8e0, cfg=cfg@entry=0x7f7b6e276640) at src/third_party/wiredtiger/src/txn/txn.c:960
#2  0x00007f7ba65016f5 in __session_commit_transaction (wt_session=0x7f7baaf9c8e0, config=<optimized out>) at src/third_party/wiredtiger/src/session/session_api.c:1664
#3  0x00007f7ba6497725 in mongo::WiredTigerRecoveryUnit::_txnClose (this=0x7f7bb1e32780, commit=<optimized out>) at /opt/mongodbtoolchain/stow/gcc-v3.zB7/include/c++/8.2.0/bits/basic_string.h:2281
#4  0x00007f7ba6497e4d in mongo::WiredTigerRecoveryUnit::_commit (this=0x7f7bb1e32780) at src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp:206
#5  0x00007f7ba6497e8a in mongo::WiredTigerRecoveryUnit::commitUnitOfWork (this=<optimized out>) at src/mongo/db/storage/wiredtiger/wiredtiger_recovery_unit.cpp:285
#6  0x00007f7ba7ce5e14 in mongo::WriteUnitOfWork::commit (this=0x7f7bb228a5d0) at /opt/mongodbtoolchain/stow/gcc-v3.zB7/include/c++/8.2.0/bits/unique_ptr.h:342
#7  0x00007f7ba72db3b6 in mongo::TransactionParticipant::Participant::_commitStorageTransaction (this=0x7f7b6e276b98, opCtx=0x7f7bb6262640) at /opt/mongodbtoolchain/stow/gcc-v3.zB7/include/c++/8.2.0/bits/unique_ptr.h:342
#8  0x00007f7ba72dfac6 in mongo::TransactionParticipant::Participant::commitPreparedTransaction (this=this@entry=0x7f7b6e276b98, opCtx=opCtx@entry=0x7f7bb6262640, commitTimestamp=commitTimestamp@entry=..., commitOplogEntryOpTime=...) at src/mongo/db/transaction_participant.cpp:1231

(gdb) p	upd
$1 = (WT_UPDATE *) 0x15
(gdb) p	upd->txnid
Cannot access memory at address 0x15

(gdb) l
209	#endif
210	
211		WT_STAT_CONN_INCR(session, txn_prepared_updates_resolved);
212	
213		for (; upd != NULL; upd = upd->next) {
214			 if (upd->txnid != txn->id)
215				continue;
216	
217			if (op->u.op_upd == NULL)
218				op->u.op_upd = upd;
(gdb)