diff --git a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Account.json b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Account.json
index 1bfc81011a..2b5aba8273 100644
--- a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Account.json
+++ b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Account.json
@@ -370,5 +370,6 @@
         "assignedUser": {
             "columns": ["assignedUserId", "deleted"]
         }
-    }
+    },
+    "optimisticConcurrencyControl": true
 }
diff --git a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Case.json b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Case.json
index 97920ee13d..ea8c4ce558 100644
--- a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Case.json
+++ b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Case.json
@@ -219,5 +219,6 @@
         "assignedUserStatus": {
             "columns": ["assignedUserId", "status"]
         }
-    }
+    },
+    "optimisticConcurrencyControl": true
 }
diff --git a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Opportunity.json b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Opportunity.json
index 2afe3be207..66db4ef22e 100644
--- a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Opportunity.json
+++ b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Opportunity.json
@@ -393,5 +393,6 @@
         "assignedUserStage": {
             "columns": ["assignedUserId", "stage"]
         }
-    }
+    },
+    "optimisticConcurrencyControl": true
 }
diff --git a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Task.json b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Task.json
index d213bfed0d..534e60795e 100644
--- a/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Task.json
+++ b/application/Espo/Modules/Crm/Resources/metadata/entityDefs/Task.json
@@ -222,5 +222,6 @@
             "columns": ["assignedUserId", "status"]
         }
     },
-    "repositoryClassName": "Espo\\Core\\Repositories\\Event"
+    "repositoryClassName": "Espo\\Core\\Repositories\\Event",
+    "optimisticConcurrencyControl": true
 }