diff --git a/ui/src/environments/index.ts b/ui/src/environments/index.ts
index d0180b57ae8..8134ed5feee 100644
--- a/ui/src/environments/index.ts
+++ b/ui/src/environments/index.ts
@@ -21,7 +21,7 @@ export interface Environment {
     readonly docsUrlPrefix: string;
     readonly links: {
 
-        readonly COMMON_STORAGE: string,
+        readonly COMMON_STORAGE: string | null,
         readonly FORGET_PASSWORD: string,
         readonly EVCS_KEBA_KECONTACT: string,
         readonly EVCS_HARDY_BARTH: string,
@@ -41,8 +41,9 @@ export interface Environment {
         readonly CONTROLLER_API_REST_READ: string,
         readonly CONTROLLER_API_REST_READWRITE: string,
 
-        readonly SETTINGS_ALERTING: string,
-        readonly SETTINGS_NETWORK_CONFIGURATION: string,
+        readonly SETTINGS_ALERTING: string | null,
+        readonly SETTINGS_NETWORK_CONFIGURATION: string | null,
+        readonly EVCS_CLUSTER: string,
 
         readonly WARRANTY: {
             readonly HOME: {
@@ -89,5 +90,5 @@ export interface Environment {
             APP_IMAGE: (language: string, appId: string) => string | null;
         },
     },
-    readonly PRODUCT_TYPES: (translate: TranslateService) => Filter
+    readonly PRODUCT_TYPES: (translate: TranslateService) => Filter | null
 }
diff --git a/ui/src/themes/openems/environments/backend-dev.ts b/ui/src/themes/openems/environments/backend-dev.ts
index 0f93f985f5d..f48b00c5e42 100644
--- a/ui/src/themes/openems/environments/backend-dev.ts
+++ b/ui/src/themes/openems/environments/backend-dev.ts
@@ -1,4 +1,3 @@
-// @ts-strict-ignore
 import { Environment } from "src/environments";
 import { theme } from "./theme";
 
diff --git a/ui/src/themes/openems/environments/backend-docker.ts b/ui/src/themes/openems/environments/backend-docker.ts
index 5ca08fb74f8..28c03b27713 100644
--- a/ui/src/themes/openems/environments/backend-docker.ts
+++ b/ui/src/themes/openems/environments/backend-docker.ts
@@ -1,12 +1,17 @@
-// @ts-strict-ignore
 import { Environment } from "src/environments";
 import { theme } from "./theme";
 
+// In docker test environment variable window.env is injected.
+// cf.
+//  - tools/docker/ui/root/etc/s6-overlay/s6-rc.d/init-nginx/run
+//  - tools/docker/ui/assets/env.template.js
+const window_env = (window as any).env as { [key: string]: string};
+
 export const environment: Environment = {
     ...theme, ...{
 
         backend: 'OpenEMS Backend',
-        url: window["env"]["websocket"],
+        url: window_env.websocket,
 
         production: true,
         debugMode: false,
diff --git a/ui/src/themes/openems/environments/backend-prod.ts b/ui/src/themes/openems/environments/backend-prod.ts
index 114c43274f1..ae5bb5eb32f 100644
--- a/ui/src/themes/openems/environments/backend-prod.ts
+++ b/ui/src/themes/openems/environments/backend-prod.ts
@@ -1,4 +1,3 @@
-// @ts-strict-ignore
 import { Environment } from "src/environments";
 import { theme } from "./theme";
 
diff --git a/ui/src/themes/openems/environments/edge-dev.ts b/ui/src/themes/openems/environments/edge-dev.ts
index a6fd796b39e..164dd04f34e 100644
--- a/ui/src/themes/openems/environments/edge-dev.ts
+++ b/ui/src/themes/openems/environments/edge-dev.ts
@@ -1,4 +1,3 @@
-// @ts-strict-ignore
 import { Environment } from "src/environments";
 import { theme } from "./theme";
 
diff --git a/ui/src/themes/openems/environments/edge-docker.ts b/ui/src/themes/openems/environments/edge-docker.ts
index 80ed1d80a99..479b15e852b 100644
--- a/ui/src/themes/openems/environments/edge-docker.ts
+++ b/ui/src/themes/openems/environments/edge-docker.ts
@@ -1,12 +1,17 @@
-// @ts-strict-ignore
 import { Environment } from "src/environments";
 import { theme } from "./theme";
 
+// In docker test environment, variable window.env is injected.
+// cf.
+//  - tools/docker/ui/root/etc/s6-overlay/s6-rc.d/init-nginx/run
+//  - tools/docker/ui/assets/env.template.js
+const window_env = (window as any).env as { [key: string]: string};
+
 export const environment: Environment = {
     ...theme, ...{
 
         backend: 'OpenEMS Edge',
-        url: window["env"]["websocket"],
+        url: window_env.websocket,
 
         production: true,
         debugMode: false,
diff --git a/ui/src/themes/openems/environments/edge-prod.ts b/ui/src/themes/openems/environments/edge-prod.ts
index 4f023294025..bcaf40f6901 100644
--- a/ui/src/themes/openems/environments/edge-prod.ts
+++ b/ui/src/themes/openems/environments/edge-prod.ts
@@ -1,4 +1,3 @@
-// @ts-strict-ignore
 import { Environment } from "src/environments";
 import { theme } from "./theme";
 
diff --git a/ui/src/themes/openems/environments/gitpod.ts b/ui/src/themes/openems/environments/gitpod.ts
index 4b8f7f22ead..1ef2f8ca499 100644
--- a/ui/src/themes/openems/environments/gitpod.ts
+++ b/ui/src/themes/openems/environments/gitpod.ts
@@ -1,4 +1,3 @@
-// @ts-strict-ignore
 import { Environment } from "src/environments";
 import { theme } from "./theme";