diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index 889eff1815..3f0fab052d 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -540,6 +540,8 @@ SimpleLruReadPage(SlruCtl ctl, int64 pageno, bool write_ok,
 
 			return slotno;
 		}
+elog(LOG, "!!!SimpleLruReadPage| pageno: %ld, slotno: %d, shared->page_status[slotno]: %d, shared->page_number[slotno]: %ld, shared->page_dirty[slotno]: %d",
+pageno, slotno, shared->page_status[slotno], shared->page_number[slotno], shared->page_dirty[slotno]);
 
 		/* We found no match; assert we selected a freeable slot */
 		Assert(shared->page_status[slotno] == SLRU_PAGE_EMPTY ||
@@ -1057,7 +1059,7 @@ SlruReportIOError(SlruCtl ctl, int64 pageno, TransactionId xid)
 	switch (slru_errcause)
 	{
 		case SLRU_OPEN_FAILED:
-			ereport(ERROR,
+			ereport(PANIC,
 					(errcode_for_file_access(),
 					 errmsg("could not access status of transaction %u", xid),
 					 errdetail("Could not open file \"%s\": %m.", path)));
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index e24a0f2fdb..03be4bb3d2 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -894,12 +894,16 @@ SerialAdd(TransactionId xid, SerCommitSeqNo minConflictCommitSeqNo)
 	{
 		firstZeroPage = SerialPage(tailXid);
 		isNewPage = true;
+elog(LOG, "!!!SerialAdd| xid: %d, serialControl->headPage: %ld, tailXid: %d, SERIAL_ENTRIESPERPAGE: %ld, firstZeroPage: %ld, targetPage: %ld, isNewPage: %d",
+xid, serialControl->headPage, tailXid, SERIAL_ENTRIESPERPAGE, firstZeroPage, targetPage, isNewPage);
 	}
 	else
 	{
 		firstZeroPage = SerialNextPage(serialControl->headPage);
 		isNewPage = SerialPagePrecedesLogically(serialControl->headPage,
 												targetPage);
+elog(LOG, "!!!SerialAdd| xid: %d, serialControl->headPage: %ld, firstZeroPage: %ld, targetPage: %ld, isNewPage: %d",
+xid, serialControl->headPage, firstZeroPage, targetPage, isNewPage);
 	}
 
 	if (!TransactionIdIsValid(serialControl->headXid)
@@ -916,6 +920,7 @@ SerialAdd(TransactionId xid, SerCommitSeqNo minConflictCommitSeqNo)
 			lock = SimpleLruGetBankLock(SerialSlruCtl, firstZeroPage);
 			LWLockAcquire(lock, LW_EXCLUSIVE);
 			slotno = SimpleLruZeroPage(SerialSlruCtl, firstZeroPage);
+elog(LOG, "!!!SerialAdd| after SimpleLruZeroPage(), firstZeroPage: %ld, slotno: %d", firstZeroPage, slotno);
 			if (firstZeroPage == targetPage)
 				break;
 			firstZeroPage = SerialNextPage(firstZeroPage);
@@ -1022,6 +1027,7 @@ SerialSetActiveSerXmin(TransactionId xid)
 		   || TransactionIdFollows(xid, serialControl->tailXid));
 
 	serialControl->tailXid = xid;
+elog(LOG, "!!!SerialSetActiveSerXmin| serialControl->tailXid: %d", serialControl->tailXid);
 
 	LWLockRelease(SerialControlLock);
 }