diff --git a/kong/clustering/services/sync/rpc.lua b/kong/clustering/services/sync/rpc.lua
index c84a10ecd76..cd1db7fe75c 100644
--- a/kong/clustering/services/sync/rpc.lua
+++ b/kong/clustering/services/sync/rpc.lua
@@ -14,6 +14,7 @@ local insert_entity_for_txn = declarative.insert_entity_for_txn
 local delete_entity_for_txn = declarative.delete_entity_for_txn
 local DECLARATIVE_HASH_KEY = constants.DECLARATIVE_HASH_KEY
 local CLUSTERING_DATA_PLANES_LATEST_VERSION_KEY = constants.CLUSTERING_DATA_PLANES_LATEST_VERSION_KEY
+local DECLARATIVE_EMPTY_CONFIG_HASH = constants.DECLARATIVE_EMPTY_CONFIG_HASH
 local DECLARATIVE_DEFAULT_WORKSPACE_KEY = constants.DECLARATIVE_DEFAULT_WORKSPACE_KEY
 local CLUSTERING_SYNC_STATUS = constants.CLUSTERING_SYNC_STATUS
 local SYNC_MUTEX_OPTS = { name = "get_delta", timeout = 0, }
@@ -22,7 +23,7 @@ local MAX_RETRY = 5
 
 local assert = assert
 local ipairs = ipairs
-local fmt = string.format
+local sub = string.sub
 local ngx_null = ngx.null
 local ngx_log = ngx.log
 local ngx_ERR = ngx.ERR
@@ -54,13 +55,29 @@ local function full_sync_result()
 end
 
 
+local function get_current_version()
+  return declarative.get_current_hash() or DECLARATIVE_EMPTY_CONFIG_HASH
+end
+
+
+local is_valid_version
+do
+  local VER_PREFIX = "v02_"
+
+  -- version string must start with 'v02_'
+  is_valid_version = function(v)
+    return sub(v, 1, 4) == VER_PREFIX
+  end
+end
+
+
 function _M:init_cp(manager)
   local purge_delay = manager.conf.cluster_data_plane_purge_delay
 
   -- CP
   -- Method: kong.sync.v2.get_delta
   -- Params: versions: list of current versions of the database
-  -- example: { default = { version = 1000, }, }
+  -- example: { default = { version = "1000", }, }
   manager.callbacks:register("kong.sync.v2.get_delta", function(node_id, current_versions)
     ngx_log(ngx_DEBUG, "[kong.sync.v2] config push (connected client)")
 
@@ -75,7 +92,7 @@ function _M:init_cp(manager)
       return nil, "default namespace does not exist inside params"
     end
 
-    -- { default = { version = 1000, }, }
+    -- { default = { version = "1000", }, }
     local default_namespace_version = default_namespace.version
     local node_info = assert(kong.rpc:get_peer_info(node_id))
 
@@ -88,7 +105,7 @@ function _M:init_cp(manager)
       labels = node_info.labels,    -- get from rpc call
       cert_details = node_info.cert_details,  -- get from rpc call
       sync_status = CLUSTERING_SYNC_STATUS.NORMAL,
-      config_hash = fmt("%032d", default_namespace_version),
+      config_hash = default_namespace_version,
       rpc_capabilities = rpc_peers and rpc_peers[node_id] or {},
     }, { ttl = purge_delay, no_broadcast_crud_event = true, })
     if not ok then
@@ -100,7 +117,8 @@ function _M:init_cp(manager)
       return nil, err
     end
 
-    if default_namespace_version == 0 or
+    --  string comparison effectively does the same as number comparison
+    if not is_valid_version(default_namespace_version) or
        default_namespace_version < latest_version then
       return full_sync_result()
     end
@@ -115,7 +133,7 @@ function _M:init_dp(manager)
   -- DP
   -- Method: kong.sync.v2.notify_new_version
   -- Params: new_versions: list of namespaces and their new versions, like:
-  -- { default = { new_version = 1000, }, }
+  -- { default = { new_version = "1000", }, }
   manager.callbacks:register("kong.sync.v2.notify_new_version", function(node_id, new_versions)
     -- TODO: currently only default is supported, and anything else is ignored
     local default_new_version = new_versions.default
@@ -128,7 +146,7 @@ function _M:init_dp(manager)
       return nil, "'new_version' key does not exist"
     end
 
-    local lmdb_ver = tonumber(declarative.get_current_hash()) or 0
+    local lmdb_ver = get_current_version()
     if lmdb_ver < version then
       -- set lastest version to shm
       kong_shm:set(CLUSTERING_DATA_PLANES_LATEST_VERSION_KEY, version)
@@ -172,11 +190,7 @@ local function do_sync()
     return nil, "rpc is not ready"
   end
 
-  local msg = { default =
-                 { version =
-                   tonumber(declarative.get_current_hash()) or 0,
-                 },
-               }
+  local msg = { default = { version = get_current_version(), }, }
 
   local ns_deltas, err = kong.rpc:call("control_plane", "kong.sync.v2.get_delta", msg)
   if not ns_deltas then
@@ -226,13 +240,13 @@ local function do_sync()
 
   local db = kong.db
 
-  local version = 0
+  local version = ""
   local opts = {}
   local crud_events = {}
   local crud_events_n = 0
 
   -- delta should look like:
-  -- { type = ..., entity = { ... }, version = 1, ws_id = ..., }
+  -- { type = ..., entity = { ... }, version = "1", ws_id = ..., }
   for _, delta in ipairs(deltas) do
     local delta_version = delta.version
     local delta_type = delta.type
@@ -308,7 +322,7 @@ local function do_sync()
     end
 
     -- delta.version should not be nil or ngx.null
-    assert(type(delta_version) == "number")
+    assert(type(delta_version) == "string")
 
     if delta_version ~= version then
       version = delta_version
@@ -316,7 +330,7 @@ local function do_sync()
   end -- for _, delta
 
   -- store current sync version
-  t:set(DECLARATIVE_HASH_KEY, fmt("%032d", version))
+  t:set(DECLARATIVE_HASH_KEY, version)
 
   -- store the correct default workspace uuid
   if default_ws_changed then
@@ -391,7 +405,7 @@ function sync_once_impl(premature, retry_count)
     return
   end
 
-  local current_version = tonumber(declarative.get_current_hash()) or 0
+  local current_version = get_current_version()
   if current_version >= latest_notified_version then
     ngx_log(ngx_DEBUG, "version already updated")
     return
diff --git a/kong/clustering/services/sync/strategies/postgres.lua b/kong/clustering/services/sync/strategies/postgres.lua
index 7bc0784c6e6..20e594d92f3 100644
--- a/kong/clustering/services/sync/strategies/postgres.lua
+++ b/kong/clustering/services/sync/strategies/postgres.lua
@@ -2,9 +2,14 @@ local _M = {}
 local _MT = { __index = _M }
 
 
+local fmt = string.format
 local ngx_null = ngx.null
 
 
+-- version string should look like: "v02_0000"
+local VERSION_FMT = "v02_%028x"
+
+
 function _M.new(db)
   local self = {
     connector = db.connector,
@@ -44,10 +49,10 @@ function _M:get_latest_version()
 
   local ver = res[1] and res[1].max
   if ver == ngx_null then
-    return 0
+    return fmt(VERSION_FMT, 0)
   end
 
-  return ver
+  return fmt(VERSION_FMT, ver)
 end
 
 
diff --git a/spec/02-integration/18-hybrid_rpc/05-sync-rpc_spec.lua b/spec/02-integration/18-hybrid_rpc/05-sync-rpc_spec.lua
index 26aa9b4b5b1..c9559c6601d 100644
--- a/spec/02-integration/18-hybrid_rpc/05-sync-rpc_spec.lua
+++ b/spec/02-integration/18-hybrid_rpc/05-sync-rpc_spec.lua
@@ -6,6 +6,13 @@ local setup = require("spec.helpers.rpc_mock.setup")
 local get_node_id = misc.get_node_id
 local DP_PREFIX = "servroot_dp"
 
+
+-- now version must be a string
+local function fmt(v)
+  return string.format("v02_%028x", v)
+end
+
+
 local function change_config()
   -- the initial sync is flaky. let's trigger a sync by creating a service
   local admin_client = helpers.admin_client()
@@ -74,12 +81,12 @@ describe("kong.sync.v2", function()
       local called = false
       mocked_cp:mock("kong.sync.v2.get_delta", function(node_id, payload)
         called = true
-        return { default = { version = 100, deltas = {} } }
+        return { default = { version = fmt(100), deltas = {} } }
       end)
 
       -- make a call from the mocked cp
       -- CP->DP: notify_new_version
-      assert(mocked_cp:call(node_id, "kong.sync.v2.notify_new_version", { default = { new_version = 100, } }))
+      assert(mocked_cp:call(node_id, "kong.sync.v2.notify_new_version", { default = { new_version = fmt(100), } }))
 
       -- DP->CP: get_delta
       -- the dp after receiving the notification will make a call to the cp
@@ -120,7 +127,7 @@ describe("kong.sync.v2", function()
       -- this is a workaround to registers the data plane node
       -- CP does not register the DP node until it receives a call from the DP
       function register_dp()
-        local res, err = mocked_dp:call("control_plane", "kong.sync.v2.get_delta", { default = { version = 0,},})
+        local res, err = mocked_dp:call("control_plane", "kong.sync.v2.get_delta", { default = { version = fmt(0),},})
         assert.is_nil(err)
         assert.is_table(res and res.default and res.default.deltas)
       end
@@ -132,7 +139,7 @@ describe("kong.sync.v2", function()
     end)
 
     it("rpc call", function()
-      local res, err = mocked_dp:call("control_plane", "kong.sync.v2.get_delta", { default = { version = 0,},})
+      local res, err = mocked_dp:call("control_plane", "kong.sync.v2.get_delta", { default = { version = fmt(0),},})
       assert.is_nil(err)
       assert.is_table(res and res.default and res.default.deltas)