diff --git a/src/MainTask.h b/src/MainTask.h
index 09795aa..3c53613 100644
--- a/src/MainTask.h
+++ b/src/MainTask.h
@@ -73,8 +73,20 @@ protected:
     }
 
     if (vars.actions.restart) {
-      vars.actions.restart = false;
       this->restartSignalTime = millis();
+      vars.actions.restart = false;
+      vars.states.restarting = true;
+
+      // save settings
+      fsSettings.updateNow();
+
+      // save sensors settings
+      fsSensorsSettings.updateNow();
+
+      // force save network settings
+      if (fsNetworkSettings.updateNow() == FD_FILE_ERR && LittleFS.begin()) {
+        fsNetworkSettings.write();
+      }
 
       Log.sinfoln(FPSTR(L_MAIN), F("Restart signal received. Restart after 10 sec."));
     }
@@ -148,20 +160,9 @@ protected:
 
 
     // restart
-    if (this->restartSignalTime > 0 && millis() - this->restartSignalTime > 10000) {
-      // save settings
-      fsSettings.updateNow();
+    if (vars.states.restarting && millis() - this->restartSignalTime > 10000) {
+      vars.states.restarting = false;
 
-      // save sensors settings
-      fsSensorsSettings.updateNow();
-
-      // force save network settings
-      if (fsNetworkSettings.updateNow() == FD_FILE_ERR && LittleFS.begin()) {
-        fsNetworkSettings.write();
-      }
-
-      this->restartSignalTime = 0;
-      this->delay(500);
       ESP.restart();
     }
   }
@@ -170,8 +171,10 @@ protected:
     unsigned int freeHeap = getFreeHeap();
     unsigned int maxFreeBlockHeap = getMaxFreeBlockHeap();
 
-    if (!this->restartSignalTime && (freeHeap < 2048 || maxFreeBlockHeap < 2048)) {
+    // critical heap
+    if (!vars.states.restarting && (freeHeap < 2048 || maxFreeBlockHeap < 2048)) {
       this->restartSignalTime = millis();
+      vars.states.restarting = true;
     }
 
     if (settings.system.logLevel < TinyLogger::Level::VERBOSE) {
diff --git a/src/MqttTask.h b/src/MqttTask.h
index a85c7e5..fe29a9c 100644
--- a/src/MqttTask.h
+++ b/src/MqttTask.h
@@ -184,6 +184,10 @@ protected:
   }
 
   void loop() {
+    if (vars.states.restarting || vars.states.upgrading) {
+      return;
+    }
+
     if (this->connected && !this->client->connected()) {
       this->connected = false;
       this->onDisconnect();
diff --git a/src/OpenThermTask.h b/src/OpenThermTask.h
index 31db6bb..c019f28 100644
--- a/src/OpenThermTask.h
+++ b/src/OpenThermTask.h
@@ -106,6 +106,10 @@ protected:
   }
 
   void loop() {
+    if (vars.states.restarting || vars.states.upgrading) {
+      return;
+    }
+
     if (this->instanceInGpio != settings.opentherm.inGpio || this->instanceOutGpio != settings.opentherm.outGpio) {
       this->setup();
 
diff --git a/src/PortalTask.h b/src/PortalTask.h
index 7e1358a..02491b5 100644
--- a/src/PortalTask.h
+++ b/src/PortalTask.h
@@ -189,6 +189,11 @@ protected:
 
       return true;
     })->setBeforeUpgradeCallback([](UpgradeHandler::UpgradeType type) -> bool {
+      if (vars.states.restarting) {
+        return false;
+      }
+
+      vars.states.upgrading = true;
       return true;
     })->setAfterUpgradeCallback([this](const UpgradeHandler::UpgradeResult& fwResult, const UpgradeHandler::UpgradeResult& fsResult) {
       unsigned short status = 200;
@@ -209,6 +214,8 @@ protected:
       response.concat(fsResult.error);
       response.concat(F("\"}}"));
       this->webServer->send(status, F("application/json"), response);
+
+      vars.states.upgrading = false;
     });
     this->webServer->addHandler(upgradeHandler);
 
@@ -247,6 +254,10 @@ protected:
         }
       }
 
+      if (vars.states.restarting) {
+        return this->webServer->send(503);
+      }
+
       const String& plain = this->webServer->arg(0);
       Log.straceln(FPSTR(L_PORTAL_WEBSERVER), F("Request /api/backup/restore %d bytes: %s"), plain.length(), plain.c_str());
 
@@ -337,6 +348,10 @@ protected:
           return this->webServer->send(401);
         }
       }
+      
+      if (vars.states.restarting) {
+        return this->webServer->send(503);
+      }
 
       const String& plain = this->webServer->arg(0);
       Log.straceln(FPSTR(L_PORTAL_WEBSERVER), F("Request /api/network/settings %d bytes: %s"), plain.length(), plain.c_str());
@@ -452,6 +467,10 @@ protected:
           return this->webServer->send(401);
         }
       }
+      
+      if (vars.states.restarting) {
+        return this->webServer->send(503);
+      }
 
       const String& plain = this->webServer->arg(0);
       Log.straceln(FPSTR(L_PORTAL_WEBSERVER), F("Request /api/settings %d bytes: %s"), plain.length(), plain.c_str());
@@ -557,6 +576,10 @@ protected:
           return this->webServer->send(401);
         }
       }
+      
+      if (vars.states.restarting) {
+        return this->webServer->send(503);
+      }
 
       #ifdef ARDUINO_ARCH_ESP8266
       if (!this->webServer->hasArg(F("id")) || this->webServer->args() != 1) {
diff --git a/src/RegulatorTask.h b/src/RegulatorTask.h
index 50a5f96..e749adf 100644
--- a/src/RegulatorTask.h
+++ b/src/RegulatorTask.h
@@ -32,6 +32,10 @@ protected:
   #endif
   
   void loop() {
+    if (vars.states.restarting || vars.states.upgrading) {
+      return;
+    }
+
     this->indoorSensorsConnected = Sensors::existsConnectedSensorsByPurpose(Sensors::Purpose::INDOOR_TEMP);
     //this->outdoorSensorsConnected = Sensors::existsConnectedSensorsByPurpose(Sensors::Purpose::OUTDOOR_TEMP);
 
diff --git a/src/SensorsTask.h b/src/SensorsTask.h
index 675401f..6519a82 100644
--- a/src/SensorsTask.h
+++ b/src/SensorsTask.h
@@ -59,6 +59,10 @@ protected:
   #endif
 
   void loop() {
+    if (vars.states.restarting || vars.states.upgrading) {
+      return;
+    }
+
     if (isPollingDallasSensors()) {
       pollingDallasSensors(false);
       this->yield();
diff --git a/src/Settings.h b/src/Settings.h
index ecb3f67..3830942 100644
--- a/src/Settings.h
+++ b/src/Settings.h
@@ -366,4 +366,9 @@ struct Variables {
     bool resetFault = false;
     bool resetDiagnostic = false;
   } actions;
+
+  struct {
+    bool restarting = false;
+    bool upgrading = false;
+  } states;
 } vars;
\ No newline at end of file