diff --git a/changelog/unreleased/kong/fix-missing-flattened-erros.yml b/changelog/unreleased/kong/fix-missing-flattened-erros.yml
new file mode 100644
index 000000000000..03a34540cde7
--- /dev/null
+++ b/changelog/unreleased/kong/fix-missing-flattened-erros.yml
@@ -0,0 +1,4 @@
+message: |
+  Fixed an issue where flattened errors had missing info when fields were lost or conflicted in a nested entity.
+type: bugfix
+scope: Core
\ No newline at end of file
diff --git a/kong/db/errors.lua b/kong/db/errors.lua
index a1f96cccd1bf..777d9237c07c 100644
--- a/kong/db/errors.lua
+++ b/kong/db/errors.lua
@@ -3,6 +3,7 @@ local pl_keys = require("pl.tablex").keys
 local nkeys = require("table.nkeys")
 local table_isarray = require("table.isarray")
 local uuid = require("kong.tools.uuid")
+local split = require("kong.tools.string").split
 
 
 local type         = type
@@ -862,6 +863,9 @@ do
       --   }
       -- }
       --
+      if type(err_t[ref.field]) == "string" then
+        err_t[ref.field] = entity_type..":"..err_t[ref.field] ..":"..ref.field
+      end
       if ref.entity == entity_type then
         local field_name = ref.field
         local field_value = entity[field_name]
@@ -1029,7 +1033,14 @@ do
         goto next_section
       end
 
-      local entities = input[entity_type]
+      local entity_type_list = split(entity_type, "|")
+      local entitys_level = input
+      for i, entity_type_elem in ipairs(entity_type_list) do
+        local next_elem = tonumber(entity_type_elem) or entity_type_elem
+        entitys_level = entitys_level[next_elem]
+      end
+
+      local entities = entitys_level
 
       if type(entities) ~= "table" then
         -- put it back into the error table
diff --git a/kong/db/schema/others/declarative_config.lua b/kong/db/schema/others/declarative_config.lua
index 7cae8ffe3c64..ab4dbeceeadb 100644
--- a/kong/db/schema/others/declarative_config.lua
+++ b/kong/db/schema/others/declarative_config.lua
@@ -400,8 +400,12 @@ local function populate_references(input, known_entities, by_id, by_key, expecte
       if key and key ~= ngx.null then
         local ok = add_to_by_key(by_key, entity_schema, item, entity, key)
         if not ok then
-          errs[entity] = errs[entity] or {}
-          errs[entity][i] = uniqueness_error_msg(entity, endpoint_key, key)
+          local errs_item_name = entity
+          if parent_entity and tostring(parent_idx) then
+            errs_item_name = parent_entity.."|"..tostring(parent_idx).."|"..entity
+          end
+          errs[errs_item_name] = errs[errs_item_name] or {}
+          errs[errs_item_name][i] = uniqueness_error_msg(entity, endpoint_key, key)
           failed = true
         end
       end
diff --git a/spec/02-integration/04-admin_api/15-off_spec.lua b/spec/02-integration/04-admin_api/15-off_spec.lua
index 554b445fcedf..fee89c2911d9 100644
--- a/spec/02-integration/04-admin_api/15-off_spec.lua
+++ b/spec/02-integration/04-admin_api/15-off_spec.lua
@@ -536,6 +536,45 @@ describe("Admin API #off", function()
         assert.equals(snis.certificate.id, certificates.id)
       end)
 
+      it("snis in certificates without certificate", function()
+        local res = assert(client:send {
+          method = "POST",
+          path = "/config?flatten_errors=1",
+          body = {
+            _format_version = "1.1",
+            consumers = {
+              {
+                username = "x",
+                basicauth_credentials = {
+                  username = "x",
+                  password = "x",
+                }
+              }
+            },
+            certificates = {
+              {
+                cert = ssl_fixtures.cert,
+                id = "d83994d2-c24c-4315-b431-ee76b6611dcb",
+                key = ssl_fixtures.key,
+                snis = {
+                  {
+                    name = "foo.example",
+                    id = "1c6e83b7-c9ad-40ac-94e8-52f5ee7bde44",
+                  },
+                }
+              }
+            },
+          },
+          headers = {
+            ["Content-Type"] = "application/json"
+          }
+        })
+
+        local body = assert.response(res).has.status(400)
+        local entities = cjson.decode(body)
+        assert.equals("snis:required field missing:certificate", entities.flattened_errors[1].errors[1].message)
+      end)
+
       it("can reload upstreams (regression test)", function()
         local config = [[
           _format_version: "1.1"
@@ -2323,6 +2362,76 @@ R6InCcH2Wh8wSeY5AuDXvu2tv9g/PW9wIJmPuKSHMA==
     }, post_config(input))
   end)
 
+  it("flatten_errors when conflicting inputs", function()
+    local conflicting_input = {
+      _format_version = "3.0",
+      consumers = {
+        {
+          username = "username1",
+          tags = {
+            "k8s-group:configuration.konghq.com",
+            "k8s-version:v1",
+            "k8s-kind:KongConsumer",
+            "k8s-namespace:default",
+            "k8s-name:consumer1"
+          },
+          basicauth_credentials = {
+            {
+              username = "username1",
+              password = "password",
+              tags = {
+                "k8s-group:",
+                "k8s-version:v1",
+                "k8s-kind:Secret",
+                "k8s-namespace:default",
+                "k8s-name:basic-1"
+              }
+            },
+            {
+              username = "username1",
+              password = "password",
+              tags = {
+                "k8s-group:",
+                "k8s-version:v1",
+                "k8s-kind:Secret",
+                "k8s-namespace:default",
+                "k8s-name:basic-2"
+              }
+            },
+          }
+        }
+      }
+    }
+    validate({
+      {
+        entity = {
+          username = "username1",
+          password = "password",
+          tags = {
+            "k8s-group:",
+            "k8s-version:v1",
+            "k8s-kind:Secret",
+            "k8s-namespace:default",
+            "k8s-name:basic-2"
+          }
+        },
+        entity_tags = {
+          "k8s-group:",
+          "k8s-version:v1",
+          "k8s-kind:Secret",
+          "k8s-namespace:default",
+          "k8s-name:basic-2"
+        },
+        entity_type = "consumers|1|basicauth_credential",
+        errors = { {
+          message = "uniqueness violation: 'basicauth_credentials' entity with username set to 'username1' already declared",
+          type = "entity",
+          }
+        }
+      },
+    }, post_config(conflicting_input))
+  end)
+
   it("preserves IDs from the input", function()
     local id = "0175e0e8-3de9-56b4-96f1-b12dcb4b6691"
     local service = {