diff --git a/ui/src/app/app.component.ts b/ui/src/app/app.component.ts
index 27d05b4410..af2069711c 100644
--- a/ui/src/app/app.component.ts
+++ b/ui/src/app/app.component.ts
@@ -21,7 +21,7 @@ export class AppComponent implements OnInit, OnDestroy {
 
   public environment = environment;
   public backUrl: string | boolean = "/";
-  public enableSideMenu: boolean;
+  public enableSideMenu: boolean = false;
   public isSystemLogEnabled: boolean = false;
 
   protected isUserAllowedToSeeOverview: boolean = false;
diff --git a/ui/src/app/edge/history/abstracthistorychart.ts b/ui/src/app/edge/history/abstracthistorychart.ts
index 7c8c70ec7b..607d4b5cff 100644
--- a/ui/src/app/edge/history/abstracthistorychart.ts
+++ b/ui/src/app/edge/history/abstracthistorychart.ts
@@ -57,6 +57,10 @@ export abstract class AbstractHistoryChart {
         borderColor: "rgba(128,128,0,1)",
     };
 
+
+    private activeQueryData: string = "";
+    private debounceTimeout: any | null = null;
+
     constructor(
         public readonly spinnerId: string,
         protected service: Service,
diff --git a/ui/src/app/edge/history/abstracthistorywidget.ts b/ui/src/app/edge/history/abstracthistorywidget.ts
index 2af3a49bc4..0000cb5edb 100644
--- a/ui/src/app/edge/history/abstracthistorywidget.ts
+++ b/ui/src/app/edge/history/abstracthistorywidget.ts
@@ -10,7 +10,7 @@ import { calculateResolution } from "./shared";
 // NOTE: Auto-refresh of widgets is currently disabled to reduce server load
 export abstract class AbstractHistoryWidget {
 
-    private activeQueryData: string;
+    private activeQueryData: string = "";
 
     //observable is used to fetch new widget data every 5 minutes
     // private refreshWidgetData = interval(600000);
diff --git a/ui/src/app/edge/history/historydataservice.ts b/ui/src/app/edge/history/historydataservice.ts
index 5abba259cc..914530c05b 100644
--- a/ui/src/app/edge/history/historydataservice.ts
+++ b/ui/src/app/edge/history/historydataservice.ts
@@ -16,7 +16,7 @@ export class HistoryDataService extends DataService {
 
   public queryChannelsTimeout: ReturnType<typeof setTimeout> | null = null;
   protected override timestamps: string[] = [];
-  private activeQueryData: string;
+  private activeQueryData: string = "";
   private channelAddresses: { [sourceId: string]: ChannelAddress } = {};
 
   constructor(
diff --git a/ui/src/app/edge/live/common/autarchy/flat/flat.ts b/ui/src/app/edge/live/common/autarchy/flat/flat.ts
index e9620384f0..a11b7f3da4 100644
--- a/ui/src/app/edge/live/common/autarchy/flat/flat.ts
+++ b/ui/src/app/edge/live/common/autarchy/flat/flat.ts
@@ -1,4 +1,3 @@
-// @ts-strict-ignore
 import { Component } from "@angular/core";
 import { AbstractFlatWidget } from "src/app/shared/components/flat/abstract-flat-widget";
 import { ChannelAddress, CurrentData, Utils } from "src/app/shared/shared";
@@ -10,7 +9,7 @@ import { ModalComponent } from "../modal/modal";
 })
 export class FlatComponent extends AbstractFlatWidget {
 
-  public percentageValue: number;
+  public percentageValue: number = 0;
 
   async presentModal() {
     const modal = await this.modalController.create({
diff --git a/ui/src/app/edge/live/common/consumption/flat/flat.ts b/ui/src/app/edge/live/common/consumption/flat/flat.ts
index 58c13f9631..4bb5c8d879 100644
--- a/ui/src/app/edge/live/common/consumption/flat/flat.ts
+++ b/ui/src/app/edge/live/common/consumption/flat/flat.ts
@@ -13,8 +13,8 @@ export class FlatComponent extends AbstractFlatWidget {
   public evcss: EdgeConfig.Component[] | null = null;
   public consumptionMeters: EdgeConfig.Component[] | null = null;
   public sumActivePower: number = 0;
-  public evcsSumOfChargePower: number;
-  public otherPower: number;
+  public evcsSumOfChargePower: number = 0;
+  public otherPower: number = 0;
   public readonly CONVERT_WATT_TO_KILOWATT = Utils.CONVERT_WATT_TO_KILOWATT;
 
   async presentModal() {
diff --git a/ui/src/app/edge/live/common/grid/flat/flat.ts b/ui/src/app/edge/live/common/grid/flat/flat.ts
index 64bc50f0ff..83ac47cf19 100644
--- a/ui/src/app/edge/live/common/grid/flat/flat.ts
+++ b/ui/src/app/edge/live/common/grid/flat/flat.ts
@@ -1,4 +1,3 @@
-// @ts-strict-ignore
 import { Component } from "@angular/core";
 import { AbstractFlatWidget } from "src/app/shared/components/flat/abstract-flat-widget";
 import { Converter } from "src/app/shared/components/shared/converter";
@@ -20,11 +19,11 @@ export class FlatComponent extends AbstractFlatWidget {
   public readonly CONVERT_WATT_TO_KILOWATT = Utils.CONVERT_WATT_TO_KILOWATT;
   public readonly GridMode = GridMode;
 
-  public gridBuyPower: number;
-  public gridSellPower: number;
+  public gridBuyPower: number = 0;
+  public gridSellPower: number = 0;
 
-  protected gridMode: number;
-  protected gridState: string;
+  protected gridMode: number = 0;
+  protected gridState: string = "";
   protected icon: Icon | null = null;
   protected isActivated: boolean = false;
 
diff --git a/ui/src/app/edge/live/common/selfconsumption/flat/flat.ts b/ui/src/app/edge/live/common/selfconsumption/flat/flat.ts
index f1bf518f2b..0c563e87cf 100644
--- a/ui/src/app/edge/live/common/selfconsumption/flat/flat.ts
+++ b/ui/src/app/edge/live/common/selfconsumption/flat/flat.ts
@@ -11,7 +11,7 @@ import { ModalComponent } from "../modal/modal";
 })
 export class FlatComponent extends AbstractFlatWidget {
 
-    public calculatedSelfConsumption: number;
+    public calculatedSelfConsumption: number = 0;
 
     async presentModal() {
         const modal = await this.modalController.create({
diff --git a/ui/src/app/edge/live/common/storage/modal/modal.component.ts b/ui/src/app/edge/live/common/storage/modal/modal.component.ts
index 6ce266a140..1cb57f604e 100644
--- a/ui/src/app/edge/live/common/storage/modal/modal.component.ts
+++ b/ui/src/app/edge/live/common/storage/modal/modal.component.ts
@@ -25,7 +25,7 @@ export class StorageModalComponent implements OnInit, OnDestroy {
     public isLastElement = Utils.isLastElement;
 
     public formGroup: FormGroup = new FormGroup({});
-    protected isAtLeastInstaller: boolean;
+    protected isAtLeastInstaller: boolean = false;
     protected isTargetTimeInValid: Map<string, boolean> = new Map();
     protected controllerIsRequiredEdgeVersion: boolean = false;
 
diff --git a/ui/src/app/shared/components/header/header.component.ts b/ui/src/app/shared/components/header/header.component.ts
index 1a4fe4dbf7..1c93c6e1d3 100644
--- a/ui/src/app/shared/components/header/header.component.ts
+++ b/ui/src/app/shared/components/header/header.component.ts
@@ -20,7 +20,7 @@ export class HeaderComponent implements OnInit, OnDestroy, AfterViewChecked {
 
     public environment = environment;
     public backUrl: string | boolean = "/";
-    public enableSideMenu: boolean;
+    public enableSideMenu: boolean = false;
     public currentPage: "EdgeSettings" | "Other" | "IndexLive" | "IndexHistory" = "Other";
     public isSystemLogEnabled: boolean = false;
 
diff --git a/ui/src/app/shared/service/service.ts b/ui/src/app/shared/service/service.ts
index cc997a4d76..0e164caff0 100644
--- a/ui/src/app/shared/service/service.ts
+++ b/ui/src/app/shared/service/service.ts
@@ -12,7 +12,7 @@ import { environment } from "src/environments";
 import { ChartConstants } from "../components/chart/chart.constants";
 import { Edge } from "../components/edge/edge";
 import { EdgeConfig } from "../components/edge/edgeconfig";
-import { JsonrpcResponseError } from "../jsonrpc/base";
+import { JsonrpcResponseError, JsonrpcResponseSuccess } from "../jsonrpc/base";
 import { GetEdgeRequest } from "../jsonrpc/request/getEdgeRequest";
 import { GetEdgesRequest } from "../jsonrpc/request/getEdgesRequest";
 import { QueryHistoricTimeseriesEnergyRequest } from "../jsonrpc/request/queryHistoricTimeseriesEnergyRequest";
@@ -56,12 +56,12 @@ export class Service extends AbstractService {
   public deviceWidth: number = 0;
   public isSmartphoneResolution: boolean = false;
   public isSmartphoneResolutionSubject: Subject<boolean> = new Subject<boolean>();
-  public activeQueryData: string;
+  public activeQueryData: string = "";
 
   /**
    * Holds the currenty selected Page Title.
    */
-  public currentPageTitle: string;
+  public currentPageTitle: string = "";
 
   /**
    * Holds reference to Websocket. This is set by Websocket in constructor.
@@ -70,14 +70,14 @@ export class Service extends AbstractService {
   /**
    * Holds the currently selected Edge.
    */
-  public readonly currentEdge: BehaviorSubject<Edge> = new BehaviorSubject<Edge>(null);
+public readonly currentEdge: BehaviorSubject<Edge | null> = new BehaviorSubject<Edge | null>(null);
 
   /**
    * Holds references of Edge-IDs (=key) to Edge objects (=value)
    */
   public readonly metadata: BehaviorSubject<{
     user: User, edges: { [edgeId: string]: Edge }
-  }> = new BehaviorSubject(null);
+  } | null> = new BehaviorSubject(null);
 
   public currentUser: User | null = null;
 
@@ -87,7 +87,7 @@ export class Service extends AbstractService {
   private currentActivatedRoute: ActivatedRoute | null = null;
 
   private queryEnergyQueue: {
-    fromDate: Date, toDate: Date, channels: ChannelAddress[], promises: { resolve, reject }[]
+    fromDate: Date, toDate: Date, channels: ChannelAddress[], promises: { resolve: (value?: JsonrpcResponseSuccess) => void; reject: (reason: any) => void }[]
   }[] = [];
   private queryEnergyTimeout: any = null;
 
@@ -108,7 +108,9 @@ export class Service extends AbstractService {
 
     // React on Language Change and update language
     translate.onLangChange.subscribe((event: LangChangeEvent) => {
-      this.setLang(Language.getByKey(event.lang));
+      if (event.lang) {
+        this.setLang(Language.getByKey(event.lang));
+    }
     });
   }
 
@@ -215,8 +217,12 @@ export class Service extends AbstractService {
   }
 
   public onLogout() {
-    this.currentEdge.next(null);
-    this.metadata.next(null);
+    if (this.currentEdge) {
+      this.currentEdge.next(null);
+    }
+    if (this.metadata) {
+      this.metadata.next(null);
+    }
     this.websocket.state.set(States.NOT_AUTHENTICATED);
     this.router.navigate(["/login"]);
   }
@@ -251,7 +257,7 @@ export class Service extends AbstractService {
           fromDate: Date,
           toDate: Date,
           channels: ChannelAddress[],
-          promises: { resolve, reject }[];
+          promises: { resolve: (value: any) => void; reject: (reason: any) => void }[]
         }[] = [];
 
         let request;
diff --git a/ui/src/app/shared/service/utils.ts b/ui/src/app/shared/service/utils.ts
index 837e37acc5..e0f1183c10 100644
--- a/ui/src/app/shared/service/utils.ts
+++ b/ui/src/app/shared/service/utils.ts
@@ -82,7 +82,7 @@ export class Utils {
    */
   public static absSafely(value: number | null): number | null {
     if (value == null) {
-      return value;
+      return null;
     } else {
       return Math.abs(value);
     }
@@ -94,7 +94,7 @@ export class Utils {
    * @param v1
    * @param v2
    */
-  public static addSafely(v1: number, v2: number): number {
+  public static addSafely(v1: number | null, v2: number | null): number | null {
     if (v1 == null) {
       return v2;
     } else if (v2 == null) {
@@ -114,6 +114,9 @@ export class Utils {
     return values
       .filter(value => value !== null && value !== undefined)
       .reduce((sum, curr) => {
+        if (curr == null) {
+          return sum;
+        }
         if (sum == null) {
           sum = curr;
         } else {
@@ -161,7 +164,7 @@ export class Utils {
    * @param v2
    * @returns
    */
-  public static compareArraysSafely<T>(v1: T[] | null, v2: T[] | null): boolean {
+  public static compareArraysSafely<T>(v1: T[] | null, v2: T[] | null): boolean | null {
     if (v1 == null || v2 == null) {
       return null;
     }
@@ -214,7 +217,7 @@ export class Utils {
    * @param orElse the default value
    * @returns      the value or the default value
    */
-  public static orElse(v: number, orElse: number): number {
+  public static orElse(v: number | null, orElse: number): number {
     if (v == null) {
       return orElse;
     } else {
@@ -552,7 +555,7 @@ export class Utils {
   }
 
   public static isDataEmpty(arg: JsonrpcResponseSuccess): boolean {
-    return Object.values(arg.result["data"])?.map(element => element as number[])?.every(element => element?.every(elem => elem == null) ?? true);
+    return Object.values(arg.result["data"] || {})?.map(element => element as number[])?.every(element => element?.every(elem => elem == null) ?? true);
   }
 
   /**
@@ -593,7 +596,7 @@ export class Utils {
    * @param consumptionMeterComponents the consumptionMeterComponents
    * @returns the other consumption
    */
-  public static calculateOtherConsumption(channelData: HistoryUtils.ChannelData, evcsComponents: EdgeConfig.Component[], consumptionMeterComponents: EdgeConfig.Component[]): number[] {
+  public static calculateOtherConsumption(channelData: HistoryUtils.ChannelData, evcsComponents: EdgeConfig.Component[], consumptionMeterComponents: EdgeConfig.Component[]): number[] | null{
 
     const totalEvcsConsumption: number[] = [];
     const totalMeteredConsumption: number[] = [];
@@ -784,14 +787,14 @@ export namespace HistoryUtils {
 
   export namespace ValueConverter {
 
-    export const NEGATIVE_AS_ZERO = (value) => {
+    export const NEGATIVE_AS_ZERO = (value: number | null): number | null  => {
       if (value == null) {
         return null;
       }
       return Math.max(0, value);
     };
 
-    export const NON_NEGATIVE = (value) => {
+    export const NON_NEGATIVE = (value: number | null): number | null => {
       if (value >= 0) {
         return value;
       } else {
@@ -862,7 +865,7 @@ export namespace TimeOfUseTariffUtils {
 
     // Error handling: Return undefined if value is not valid
     if (value === undefined || value === null || Number.isNaN(Number.parseInt(value.toString()))) {
-      return;
+      return "";
     }
 
     const socLabel = translate.instant("General.soc");
diff --git a/ui/src/app/shared/shared.module.ts b/ui/src/app/shared/shared.module.ts
index 75cca82971..9394e9f19c 100644
--- a/ui/src/app/shared/shared.module.ts
+++ b/ui/src/app/shared/shared.module.ts
@@ -49,11 +49,11 @@ export function SubnetmaskValidator(control: FormControl): ValidationErrors {
   return /^(255)\.(0|128|192|224|240|248|252|254|255)\.(0|128|192|224|240|248|252|254|255)\.(0|128|192|224|240|248|252|254|255)/.test(control.value) ? null : { "subnetmask": true };
 }
 
-export function IpValidatorMessage(err, field: FormlyFieldConfig) {
+export function IpValidatorMessage(err: any, field: FormlyFieldConfig) {
   return `"${field.formControl.value}" is not a valid IP Address`;
 }
 
-export function SubnetmaskValidatorMessage(err, field: FormlyFieldConfig) {
+export function SubnetmaskValidatorMessage(err: any, field: FormlyFieldConfig) {
   return `"${field.formControl.value}" is not a valid Subnetmask`;
 }
 
diff --git a/ui/src/app/shared/type/widget.ts b/ui/src/app/shared/type/widget.ts
index 5f72e25e0c..f6524e7173 100644
--- a/ui/src/app/shared/type/widget.ts
+++ b/ui/src/app/shared/type/widget.ts
@@ -48,8 +48,8 @@ export type Icon = {
 };
 
 export class Widget {
-    public name: WidgetNature | WidgetFactory | string;
-    public componentId: string;
+    public name: WidgetNature | WidgetFactory | string = "";
+    public componentId: string = "";
 }
 
 export class Widgets {
diff --git a/ui/src/app/user/user.component.ts b/ui/src/app/user/user.component.ts
index 694549cf3b..f3a717cbd9 100644
--- a/ui/src/app/user/user.component.ts
+++ b/ui/src/app/user/user.component.ts
@@ -199,7 +199,9 @@ export class UserComponent implements OnInit {
   public enableAndDisableFormFields(): boolean {
 
     this.userInformationFields = this.userInformationFields.map(field => {
-      field.props.disabled = !field.props.disabled;
+      if (field.props) {
+        field.props.disabled = !field.props.disabled;
+      }
       return field;
     });