diff --git a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
index 559dcc7..571b352 100644
--- a/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/dm-snapshot-merge/snapuserd_worker.cpp
@@ -103,7 +103,7 @@
     ssize_t rv = reader_->ReadData(cow_op, buffer, BLOCK_SZ);
     if (rv != BLOCK_SZ) {
         SNAP_LOG(ERROR) << "ProcessReplaceOp failed for block " << cow_op->new_block
-                        << ", return = " << rv;
+                        << ", return = " << rv << ", COW operation = " << *cow_op;
         return false;
     }
     return true;
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp
index b9ecfa5..5cb13e8 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/read_worker.cpp
@@ -283,7 +283,8 @@
                 // We found the sector in mapping. Check the type of COW OP and
                 // process it.
                 if (!ProcessCowOp(it->second, buffer)) {
-                    SNAP_LOG(ERROR) << "ProcessCowOp failed";
+                    SNAP_LOG(ERROR)
+                            << "ProcessCowOp failed, sector = " << sector << ", size = " << sz;
                     return false;
                 }