diff --git a/tests/test_zfsautobackup.py b/tests/test_zfsautobackup.py
index 2a77e5d..4bdc1bf 100644
--- a/tests/test_zfsautobackup.py
+++ b/tests/test_zfsautobackup.py
@@ -545,11 +545,10 @@ test_target1/test_source2/fs2/sub@test-20101111000000  canmount  -         -
             # should fail, now incompatible
             self.assertTrue(ZfsAutobackup("test test_target1 --no-progress --verbose --allow-empty".split(" ")).run())
 
-        # FIXME: tries to get the guid of the non existing snapshot because of --test mode
         with mocktime("20101111000003"):
             # --test should succeed by destroying incompatibles
             self.assertFalse(ZfsAutobackup(
-                "test test_target1 --no-progress --verbose --allow-empty --destroy-incompatible --test --debug".split(
+                "test test_target1 --no-progress --verbose --allow-empty --destroy-incompatible --test".split(
                     " ")).run())
 
         with mocktime("20101111000003"):
diff --git a/zfs_autobackup/ZfsDataset.py b/zfs_autobackup/ZfsDataset.py
index 882f943..093c25e 100644
--- a/zfs_autobackup/ZfsDataset.py
+++ b/zfs_autobackup/ZfsDataset.py
@@ -1116,9 +1116,14 @@ class ZfsDataset:
                         return source_snapshot, target_snapshot
 
                 # Extensive GUID search (slower but works with all names)
-                source_bookmark_snapshot = self.find_guid_bookmark_snapshot(target_snapshot.properties['guid'])
-                if source_bookmark_snapshot is not None:
-                    return source_bookmark_snapshot, target_snapshot
+                try:
+                    source_bookmark_snapshot = self.find_guid_bookmark_snapshot(target_snapshot.properties['guid'])
+                    if source_bookmark_snapshot is not None:
+                        return source_bookmark_snapshot, target_snapshot
+                except ExecuteError as e:
+                    # in readonly mode we igore a failed property read for non existing snapshots
+                    if not self.zfs_node.readonly:
+                        raise e
 
             raise (Exception("Cant find common bookmark or snapshot with target."))