diff --git a/application/src/main/java/org/thingsboard/server/service/notification/DefaultNotificationCenter.java b/application/src/main/java/org/thingsboard/server/service/notification/DefaultNotificationCenter.java
index 561ce9f4ee..f6c77691da 100644
--- a/application/src/main/java/org/thingsboard/server/service/notification/DefaultNotificationCenter.java
+++ b/application/src/main/java/org/thingsboard/server/service/notification/DefaultNotificationCenter.java
@@ -182,7 +182,7 @@ public class DefaultNotificationCenter extends AbstractSubscriptionService imple
         NotificationRequest notificationRequest = NotificationRequest.builder()
                 .tenantId(tenantId)
                 .template(template)
-                .targets(List.of(EntityId.NULL_UUID)) // TODO: refactor
+                .targets(List.of(EntityId.NULL_UUID)) // this is temporary and will be removed when 'create from scratch' functionality is implemented for recipients
                 .status(NotificationRequestStatus.PROCESSING)
                 .build();
         try {
diff --git a/application/src/main/java/org/thingsboard/server/service/security/auth/jwt/settings/DefaultJwtSettingsService.java b/application/src/main/java/org/thingsboard/server/service/security/auth/jwt/settings/DefaultJwtSettingsService.java
index 8ab8cec5f2..d350a86f91 100644
--- a/application/src/main/java/org/thingsboard/server/service/security/auth/jwt/settings/DefaultJwtSettingsService.java
+++ b/application/src/main/java/org/thingsboard/server/service/security/auth/jwt/settings/DefaultJwtSettingsService.java
@@ -46,7 +46,7 @@ public class DefaultJwtSettingsService implements JwtSettingsService {
     private final AdminSettingsService adminSettingsService;
     @Lazy
     private final Optional<TbClusterService> tbClusterService;
-    private final NotificationCenter notificationCenter;
+    private final Optional<NotificationCenter> notificationCenter;
     private final JwtSettingsValidator jwtSettingsValidator;
 
     @Value("${security.jwt.tokenExpirationTime:9000}")
@@ -128,7 +128,9 @@ public class DefaultJwtSettingsService implements JwtSettingsService {
                         log.warn("WARNING: The platform is configured to use default JWT Signing Key. " +
                                 "This is a security issue that needs to be resolved. Please change the JWT Signing Key using the Web UI. " +
                                 "Navigate to \"System settings -> Security settings\" while logged in as a System Administrator.");
-                        notificationCenter.sendGeneralWebNotification(TenantId.SYS_TENANT_ID, new SystemAdministratorsFilter(), DefaultNotifications.jwtSigningKeyIssue.toTemplate());
+                        notificationCenter.ifPresent(notificationCenter -> {
+                            notificationCenter.sendGeneralWebNotification(TenantId.SYS_TENANT_ID, new SystemAdministratorsFilter(), DefaultNotifications.jwtSigningKeyIssue.toTemplate());
+                        });
                     }
                     this.jwtSettings = result;
                 }
diff --git a/application/src/test/java/org/thingsboard/server/service/security/auth/JwtTokenFactoryTest.java b/application/src/test/java/org/thingsboard/server/service/security/auth/JwtTokenFactoryTest.java
index b7dc40ec6d..7bb4f1e559 100644
--- a/application/src/test/java/org/thingsboard/server/service/security/auth/JwtTokenFactoryTest.java
+++ b/application/src/test/java/org/thingsboard/server/service/security/auth/JwtTokenFactoryTest.java
@@ -16,14 +16,22 @@
 package org.thingsboard.server.service.security.auth;
 
 import io.jsonwebtoken.Claims;
-import org.junit.BeforeClass;
+import org.junit.Before;
 import org.junit.Test;
+import org.thingsboard.common.util.JacksonUtil;
+import org.thingsboard.rule.engine.api.NotificationCenter;
+import org.thingsboard.server.common.data.AdminSettings;
 import org.thingsboard.server.common.data.id.CustomerId;
 import org.thingsboard.server.common.data.id.TenantId;
 import org.thingsboard.server.common.data.id.UserId;
+import org.thingsboard.server.common.data.notification.NotificationDeliveryMethod;
+import org.thingsboard.server.common.data.notification.targets.platform.SystemAdministratorsFilter;
 import org.thingsboard.server.common.data.security.Authority;
 import org.thingsboard.server.common.data.security.model.JwtSettings;
 import org.thingsboard.server.common.data.security.model.JwtToken;
+import org.thingsboard.server.dao.settings.AdminSettingsService;
+import org.thingsboard.server.service.security.auth.jwt.settings.DefaultJwtSettingsService;
+import org.thingsboard.server.service.security.auth.jwt.settings.DefaultJwtSettingsValidator;
 import org.thingsboard.server.service.security.auth.jwt.settings.JwtSettingsService;
 import org.thingsboard.server.service.security.model.SecurityUser;
 import org.thingsboard.server.service.security.model.UserPrincipal;
@@ -33,28 +41,40 @@ import org.thingsboard.server.service.security.model.token.RawAccessJwtToken;
 
 import java.util.Calendar;
 import java.util.Date;
+import java.util.Optional;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.mockito.BDDMockito.willReturn;
+import static org.mockito.ArgumentMatchers.argThat;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.ArgumentMatchers.isA;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
 
 public class JwtTokenFactoryTest {
 
-    private static JwtTokenFactory tokenFactory;
-    private static JwtSettings jwtSettings;
+    private JwtTokenFactory tokenFactory;
+    private AdminSettingsService adminSettingsService;
+    private NotificationCenter notificationCenter;
+    private JwtSettingsService jwtSettingsService;
 
-    @BeforeClass
-    public static void beforeAll() {
+    private JwtSettings jwtSettings;
+
+    @Before
+    public void beforeEach() {
         jwtSettings = new JwtSettings();
         jwtSettings.setTokenIssuer("tb");
         jwtSettings.setTokenSigningKey("abewafaf");
         jwtSettings.setTokenExpirationTime((int) TimeUnit.HOURS.toSeconds(2));
         jwtSettings.setRefreshTokenExpTime((int) TimeUnit.DAYS.toSeconds(7));
 
-        JwtSettingsService jwtSettingsService = mock(JwtSettingsService.class);
-        willReturn(jwtSettings).given(jwtSettingsService).getJwtSettings();
+        adminSettingsService = mock(AdminSettingsService.class);
+        notificationCenter = mock(NotificationCenter.class);
+        jwtSettingsService = mockJwtSettingsService();
+        mockJwtSettings(jwtSettings);
 
         tokenFactory = new JwtTokenFactory(jwtSettingsService);
     }
@@ -150,6 +170,33 @@ public class JwtTokenFactoryTest {
         });
     }
 
+    @Test
+    public void testJwtSigningKeyIssueNotification() {
+        JwtSettings badJwtSettings = jwtSettings;
+        badJwtSettings.setTokenSigningKey(JwtSettingsService.TOKEN_SIGNING_KEY_DEFAULT);
+        mockJwtSettings(badJwtSettings);
+        jwtSettingsService = mockJwtSettingsService();
+
+        for (int i = 0; i < 5; i++) { // to check if notification is not sent twice
+            jwtSettingsService.getJwtSettings();
+        }
+        verify(notificationCenter, times(1)).sendGeneralWebNotification(eq(TenantId.SYS_TENANT_ID),
+                isA(SystemAdministratorsFilter.class), argThat(template -> template.getConfiguration().getDeliveryMethodsTemplates().get(NotificationDeliveryMethod.WEB)
+                        .getBody().contains("The platform is configured to use default JWT Signing Key")));
+    }
+
+    private void mockJwtSettings(JwtSettings settings) {
+        AdminSettings adminJwtSettings = new AdminSettings();
+        adminJwtSettings.setJsonValue(JacksonUtil.valueToTree(settings));
+        when(adminSettingsService.findAdminSettingsByKey(TenantId.SYS_TENANT_ID, JwtSettingsService.ADMIN_SETTINGS_JWT_KEY))
+                .thenReturn(adminJwtSettings);
+    }
+
+    private DefaultJwtSettingsService mockJwtSettingsService() {
+        return new DefaultJwtSettingsService(adminSettingsService, Optional.empty(),
+                Optional.of(notificationCenter), new DefaultJwtSettingsValidator());
+    }
+
     private void checkExpirationTime(JwtToken jwtToken, int tokenLifetime) {
         Claims claims = tokenFactory.parseTokenClaims(jwtToken).getBody();
         assertThat(claims.getExpiration()).matches(actualExpirationTime -> {
diff --git a/dao/src/main/java/org/thingsboard/server/dao/notification/DefaultNotifications.java b/dao/src/main/java/org/thingsboard/server/dao/notification/DefaultNotifications.java
index 34a2839f92..29c7928a24 100644
--- a/dao/src/main/java/org/thingsboard/server/dao/notification/DefaultNotifications.java
+++ b/dao/src/main/java/org/thingsboard/server/dao/notification/DefaultNotifications.java
@@ -66,6 +66,9 @@ import static org.thingsboard.server.dao.DaoUtil.toUUIDs;
 @RequiredArgsConstructor
 public class DefaultNotifications {
 
+    private static final String YELLOW_COLOR = "#F9D916";
+    private static final String RED_COLOR = "#e91a1a";
+
     public static final DefaultNotification maintenanceWork = DefaultNotification.builder()
             .name("Maintenance work notification")
             .subject("Infrastructure maintenance")
@@ -77,7 +80,7 @@ public class DefaultNotifications {
             .type(NotificationType.ENTITIES_LIMIT)
             .subject("${entityType}s limit will be reached soon for tenant ${tenantName}")
             .text("${entityType}s usage: ${currentCount}/${limit} (${percents}%)")
-            .icon("warning").color("#F9D916")
+            .icon("warning").color(YELLOW_COLOR)
             .rule(DefaultRule.builder()
                     .name("Entities count limit (sysadmin)")
                     .triggerConfig(EntitiesLimitNotificationRuleTriggerConfig.builder()
@@ -100,7 +103,7 @@ public class DefaultNotifications {
             .type(NotificationType.API_USAGE_LIMIT)
             .subject("${feature} feature will be disabled soon for tenant ${tenantName}")
             .text("Usage: ${currentValue} out of ${limit} ${unitLabel}s")
-            .icon("warning").color("#F9D916")
+            .icon("warning").color(YELLOW_COLOR)
             .rule(DefaultRule.builder()
                     .name("API feature warning (sysadmin)")
                     .triggerConfig(ApiUsageLimitNotificationRuleTriggerConfig.builder()
@@ -123,7 +126,7 @@ public class DefaultNotifications {
             .type(NotificationType.API_USAGE_LIMIT)
             .subject("${feature} feature was disabled for tenant ${tenantName}")
             .text("Used ${currentValue} out of ${limit} ${unitLabel}s")
-            .icon("block").color("#e91a1a")
+            .icon("block").color(RED_COLOR)
             .rule(DefaultRule.builder()
                     .name("API feature disabled (sysadmin)")
                     .triggerConfig(ApiUsageLimitNotificationRuleTriggerConfig.builder()
@@ -147,7 +150,7 @@ public class DefaultNotifications {
             .type(NotificationType.RATE_LIMITS)
             .subject("Rate limits exceeded")
             .text("Rate limits for ${api} exceeded")
-            .icon("block").color("#e91a1a")
+            .icon("block").color(RED_COLOR)
             .rule(DefaultRule.builder()
                     .name("Per-tenant rate limits exceeded")
                     .triggerConfig(RateLimitsNotificationRuleTriggerConfig.builder()
@@ -164,7 +167,7 @@ public class DefaultNotifications {
             .type(NotificationType.RATE_LIMITS)
             .subject("Rate limits exceeded")
             .text("Rate limits for ${api} exceeded for '${limitLevelEntityName}'")
-            .icon("block").color("#e91a1a")
+            .icon("block").color(RED_COLOR)
             .rule(DefaultRule.builder()
                     .name("Per-entity rate limits exceeded")
                     .triggerConfig(RateLimitsNotificationRuleTriggerConfig.builder()
@@ -328,7 +331,7 @@ public class DefaultNotifications {
             .type(NotificationType.GENERAL)
             .subject("WARNING: security issue")
             .text("The platform is configured to use default JWT Signing Key. Please change it on the security settings page")
-            .icon("warning").color("#F9D916")
+            .icon("warning").color(YELLOW_COLOR)
             .button("Go to settings").link("/security-settings/general")
             .build();