diff --git a/src/khepri_machine.erl b/src/khepri_machine.erl
index 7b196535..23e4827c 100644
--- a/src/khepri_machine.erl
+++ b/src/khepri_machine.erl
@@ -98,8 +98,8 @@
 %% For internal use only.
 -export([clear_cache/1,
          ack_triggers_execution/2,
-         split_query_options/1,
-         split_command_options/1,
+         split_query_options/2,
+         split_command_options/2,
          split_put_options/1,
          insert_or_update_node/6,
          delete_matching_nodes/4,
@@ -283,7 +283,7 @@ fold(StoreId, PathPattern, Fun, Acc, Options)
        is_function(Fun, 3) ->
     PathPattern1 = khepri_path:from_string(PathPattern),
     khepri_path:ensure_is_valid(PathPattern1),
-    {QueryOptions, TreeOptions} = split_query_options(Options),
+    {QueryOptions, TreeOptions} = split_query_options(StoreId, Options),
     Query = fun(State) ->
                     Tree = get_tree(State),
                     try
@@ -348,7 +348,8 @@ put(StoreId, PathPattern, Payload, Options)
     PathPattern1 = khepri_path:from_string(PathPattern),
     khepri_path:ensure_is_valid(PathPattern1),
     Payload1 = khepri_payload:prepare(Payload),
-    {CommandOptions, TreeAndPutOptions} = split_command_options(Options),
+    {CommandOptions, TreeAndPutOptions} = split_command_options(
+                                            StoreId, Options),
     Command = #put{path = PathPattern1,
                    payload = Payload1,
                    options = TreeAndPutOptions},
@@ -376,7 +377,7 @@ put(_StoreId, PathPattern, Payload, _Options) ->
 delete(StoreId, PathPattern, Options) when ?IS_KHEPRI_STORE_ID(StoreId) ->
     PathPattern1 = khepri_path:from_string(PathPattern),
     khepri_path:ensure_is_valid(PathPattern1),
-    {CommandOptions, TreeOptions} = split_command_options(Options),
+    {CommandOptions, TreeOptions} = split_command_options(StoreId, Options),
     %% TODO: Ensure `PutOptions' are not set this map.
     Command = #delete{path = PathPattern1,
                       options = TreeOptions},
@@ -722,14 +723,17 @@ get_projections_state(StoreId, Options)
             end,
     process_query(StoreId, Query, Options).
 
--spec split_query_options(Options) -> {QueryOptions, TreeOptions} when
+-spec split_query_options(StoreId | Pid, Options) ->
+    {QueryOptions, TreeOptions} when
+      StoreId :: khepri:store_id(),
+      Pid :: pid(),
       Options :: QueryOptions | TreeOptions,
       QueryOptions :: khepri:query_options(),
       TreeOptions :: khepri:tree_options().
 %% @private
 
-split_query_options(Options) ->
-    Options1 = set_default_options(Options),
+split_query_options(StoreId, Options) ->
+    Options1 = set_default_options(StoreId, Options),
     maps:fold(
       fun
           (Option, Value, {Q, T}) when
@@ -748,15 +752,17 @@ split_query_options(Options) ->
               {Q, T1}
       end, {#{}, #{}}, Options1).
 
--spec split_command_options(Options) ->
+-spec split_command_options(StoreId | Pid, Options) ->
     {CommandOptions, TreeAndPutOptions} when
+      StoreId :: khepri:store_id(),
+      Pid :: pid(),
       Options :: CommandOptions | TreeAndPutOptions,
       CommandOptions :: khepri:command_options(),
       TreeAndPutOptions :: khepri:tree_options() | khepri:put_options().
 %% @private
 
-split_command_options(Options) ->
-    Options1 = set_default_options(Options),
+split_command_options(StoreId, Options) ->
+    Options1 = set_default_options(StoreId, Options),
     maps:fold(
       fun
           (Option, Value, {C, TP}) when
@@ -799,7 +805,7 @@ split_put_options(TreeAndPutOptions) ->
               {T1, P}
       end, {#{}, #{}}, TreeAndPutOptions).
 
-set_default_options(Options) ->
+set_default_options(StoreId, Options) ->
     %% By default, return payload-related properties. The caller can set
     %% `props_to_return' to an empty map to get a minimal return value.
     Options1 = case Options of
@@ -808,7 +814,21 @@ set_default_options(Options) ->
                    _ ->
                        Options#{props_to_return => ?DEFAULT_PROPS_TO_RETURN}
                end,
-    Options1.
+    %% We need to remove `delete_reason' from the list if the whole cluster is
+    %% still using a machine version that doesn't know about it. Otherwise old
+    %% versions of Khepri will crash when gathering the properties.
+    PropsToReturn0 = maps:get(props_to_return, Options1),
+    PropsToReturn1 = case effective_version(StoreId) of
+                         {ok, EffectiveMacVer} when EffectiveMacVer >= 2 ->
+                             PropsToReturn0;
+                         _ ->
+                             %% `delete_reason' was added in machine version
+                             %% 2. Also, previous versions didn't ignore
+                             %% unknown props_to_return and crashed.
+                             PropsToReturn0 -- [delete_reason]
+                     end,
+    Options2 = Options1#{props_to_return => PropsToReturn1},
+    Options2.
 
 -spec process_command(StoreId, Command, Options) -> Ret when
       StoreId :: khepri:store_id(),
@@ -1736,13 +1756,14 @@ which_module(2) -> ?MODULE;
 which_module(1) -> ?MODULE;
 which_module(0) -> ?MODULE.
 
--spec effective_version(StoreId) -> Ret when
+-spec effective_version(StoreId | Pid) -> Ret when
       StoreId :: khepri:store_id(),
+      Pid :: pid(),
       Ret :: khepri:ok(EffectiveMacVer) | khepri:error(),
       EffectiveMacVer :: ra_machine:version().
 %% @doc Returns the effective state machine version of the local Ra server.
 
-effective_version(StoreId) ->
+effective_version(StoreId) when ?IS_KHEPRI_STORE_ID(StoreId) ->
     ThisNode = node(),
     RaServer = khepri_cluster:node_to_member(StoreId, ThisNode),
     case ra_counters:counters(RaServer, [effective_machine_version]) of
@@ -1760,6 +1781,26 @@ effective_version(StoreId) ->
                                   error => Error}),
                     {error, Reason}
             end
+    end;
+effective_version(Pid) when is_pid(Pid) ->
+    %% FIXME: When called from the machine/Ra server, we don't have the
+    %% `StoreId' because we didn't keep it in state even though it is available
+    %% in the init arguments... This will need a change to the state record
+    %% unfortunalety.
+    %%
+    %% Meanwhile, we can query the registered name for the calling process, it
+    %% matches the `StoreId'. This is an internal Ra implementation detail, so
+    %% this should be fixed the next time we have a reason to update the state
+    %% record.
+    case erlang:process_info(Pid, registered_name) of
+        {registered_name, StoreId} when is_atom(StoreId) ->
+            effective_version(StoreId);
+        [] ->
+            Reason = ?khepri_error(
+                        effective_machine_version_not_defined,
+                        #{ra_server_pid => Pid,
+                          error => no_registered_name_for_pid}),
+            {error, Reason}
     end.
 
 %% -------------------------------------------------------------------
diff --git a/src/khepri_tx.erl b/src/khepri_tx.erl
index a9a4d83c..863a9653 100644
--- a/src/khepri_tx.erl
+++ b/src/khepri_tx.erl
@@ -468,7 +468,8 @@ count(PathPattern, Options) ->
     {State, _SideEffects} = khepri_tx_adv:get_tx_state(),
     Tree = khepri_machine:get_tree(State),
     Fun = fun khepri_tree:count_node_cb/3,
-    {_QueryOptions, TreeOptions} = khepri_machine:split_query_options(Options),
+    {_QueryOptions, TreeOptions} =
+    khepri_machine:split_query_options(self(), Options),
     TreeOptions1 = TreeOptions#{expect_specific_node => false},
     Ret = khepri_tree:fold(Tree, PathPattern1, Fun, 0, TreeOptions1),
     case Ret of
@@ -518,7 +519,8 @@ fold(PathPattern, Fun, Acc, Options) ->
     PathPattern1 = khepri_tx_adv:path_from_string(PathPattern),
     {State, _SideEffects} = khepri_tx_adv:get_tx_state(),
     Tree = khepri_machine:get_tree(State),
-    {_QueryOptions, TreeOptions} = khepri_machine:split_query_options(Options),
+    {_QueryOptions, TreeOptions} =
+    khepri_machine:split_query_options(self(), Options),
     TreeOptions1 = TreeOptions#{expect_specific_node => false},
     Ret = khepri_tree:fold(Tree, PathPattern1, Fun, Acc, TreeOptions1),
     case Ret of
diff --git a/src/khepri_tx_adv.erl b/src/khepri_tx_adv.erl
index 5ab4efa0..ab6d2cfd 100644
--- a/src/khepri_tx_adv.erl
+++ b/src/khepri_tx_adv.erl
@@ -129,7 +129,8 @@ get_many(PathPattern, Options) ->
 
 do_get_many(PathPattern, Fun, Acc, Options) ->
     PathPattern1 = path_from_string(PathPattern),
-    {_QueryOptions, TreeOptions} = khepri_machine:split_query_options(Options),
+    {_QueryOptions, TreeOptions} =
+    khepri_machine:split_query_options(self(), Options),
     {State, _SideEffects} = get_tx_state(),
     Tree = khepri_machine:get_tree(State),
     Ret = khepri_tree:fold(Tree, PathPattern1, Fun, Acc, TreeOptions),
@@ -211,7 +212,7 @@ put_many(PathPattern, Data, Options) ->
     PathPattern1 = path_from_string(PathPattern),
     Payload1 = khepri_payload:wrap(Data),
     {_CommandOptions, TreeAndPutOptions} =
-    khepri_machine:split_command_options(Options),
+    khepri_machine:split_command_options(self(), Options),
     {TreeOptions, PutOptions} =
     khepri_machine:split_put_options(TreeAndPutOptions),
     %% TODO: Ensure `CommandOptions' is unset.
@@ -402,7 +403,7 @@ delete_many(PathPattern, Options) ->
     ensure_updates_are_allowed(),
     PathPattern1 = path_from_string(PathPattern),
     {_CommandOptions, TreeOptions} =
-    khepri_machine:split_command_options(Options),
+    khepri_machine:split_command_options(self(), Options),
     %% TODO: Ensure `CommandOptions' is empty and `TreeOptions' doesn't
     %% contains put options.
     Fun = fun(State, SideEffects) ->