3 files changed, 12 insertions, 0 deletions
diff --git a/src/org/traccar/database/DeviceManager.java b/src/org/traccar/database/DeviceManager.java
index 4aafe6631..5d123f9b8 100644
--- a/src/org/traccar/database/DeviceManager.java
+++ b/src/org/traccar/database/DeviceManager.java
@@ -57,6 +57,12 @@ public class DeviceManager extends BaseObjectManager<Device> implements Identity
     public DeviceManager(DataManager dataManager) {
         super(dataManager, Device.class);
         this.config = Context.getConfig();
+        if (devicesByPhone == null) {
+            devicesByPhone = new ConcurrentHashMap<>();
+        }
+        if (devicesByUniqueId == null) {
+            devicesByUniqueId = new ConcurrentHashMap<>();
+        }
         dataRefreshDelay = config.getLong("database.refreshDelay", DEFAULT_REFRESH_DELAY) * 1000;
         lookupGroupsAttribute = config.getBoolean("deviceManager.lookupGroupsAttribute");
         fallbackToText = config.getBoolean("command.fallbackToSms");
diff --git a/src/org/traccar/database/DriversManager.java b/src/org/traccar/database/DriversManager.java
index d3866a5f0..9defa1931 100644
--- a/src/org/traccar/database/DriversManager.java
+++ b/src/org/traccar/database/DriversManager.java
@@ -27,6 +27,9 @@ public class DriversManager extends ExtendedObjectManager<Driver> {
 
     public DriversManager(DataManager dataManager) {
         super(dataManager, Driver.class);
+        if (driversByUniqueId == null) {
+            driversByUniqueId = new ConcurrentHashMap<>();
+        }
     }
 
     private void putUniqueDriverId(Driver driver) {
diff --git a/src/org/traccar/database/UsersManager.java b/src/org/traccar/database/UsersManager.java
index 28e6a31b2..ed39f6cfa 100644
--- a/src/org/traccar/database/UsersManager.java
+++ b/src/org/traccar/database/UsersManager.java
@@ -29,6 +29,9 @@ public class UsersManager extends SimpleObjectManager<User> {
 
     public UsersManager(DataManager dataManager) {
         super(dataManager, User.class);
+        if (usersTokens == null) {
+            usersTokens = new ConcurrentHashMap<>();
+        }
     }
 
     private void putToken(User user) {