diff --git a/src/app/superadmin/users/users.component.ts b/src/app/superadmin/users/users.component.ts
index 4995c3fe3e460fae8764040bf5a2ad8ecbcd00d3..a4ac3999a4f501da6e60ec2942daa9c3b353ea05 100644
--- a/src/app/superadmin/users/users.component.ts
+++ b/src/app/superadmin/users/users.component.ts
@@ -34,7 +34,7 @@ export class UsersComponent implements OnInit, OnDestroy {
   public displayedWorkspaceColumns = ['selectCheckbox', 'label'];
   private logindataSubscription: Subscription = null;
 
-  @ViewChild(MatSort) sort: MatSort;
+  @ViewChild(MatSort, { static: false }) sort: MatSort;
 
   constructor(
     private bs: BackendService,
diff --git a/src/app/superadmin/workspaces/workspaces.component.ts b/src/app/superadmin/workspaces/workspaces.component.ts
index a5f44d3a7b3d2957df680794f7d343a2141ce963..cd077da3d7460f9311498661f147e97cb1ac0b3f 100644
--- a/src/app/superadmin/workspaces/workspaces.component.ts
+++ b/src/app/superadmin/workspaces/workspaces.component.ts
@@ -34,7 +34,7 @@ export class WorkspacesComponent implements OnInit, OnDestroy {
   public UserlistDatasource: MatTableDataSource<IdRoleData>;
   public displayedUserColumns = ['selectCheckbox', 'name'];
 
-  @ViewChild(MatSort) sort: MatSort;
+  @ViewChild(MatSort, { static: false }) sort: MatSort;
 
   constructor(
     private bs: BackendService,
diff --git a/src/app/workspace/files/files.component.ts b/src/app/workspace/files/files.component.ts
index f8d9b72fa8fbbd18e3437cda3ca28f912040a9b9..35dd0ed6f7b3b82417fe83b23e9e7112bead4419 100644
--- a/src/app/workspace/files/files.component.ts
+++ b/src/app/workspace/files/files.component.ts
@@ -37,7 +37,7 @@ export class FilesComponent implements OnInit, OnDestroy {
   public checkWarnings = [];
   public checkInfos = [];
 
-  @ViewChild(MatSort) sort: MatSort;
+  @ViewChild(MatSort, { static: true }) sort: MatSort;
 
   constructor(
     @Inject('SERVER_URL') private serverUrl: string,
diff --git a/src/app/workspace/monitor/monitor.component.ts b/src/app/workspace/monitor/monitor.component.ts
index c69704e8f2cf682a343f1eb18e085d79341cbc68..b8987e79b4149a5f5a8567a7e37c84ef6539f624 100644
--- a/src/app/workspace/monitor/monitor.component.ts
+++ b/src/app/workspace/monitor/monitor.component.ts
@@ -24,7 +24,7 @@ export class MonitorComponent implements OnInit, OnDestroy {
   public tableselectionCheckbox = new SelectionModel<MonitorData>(true, []);
   private workspaceIdSubscription: Subscription = null;
   public dataLoading = false;
-  @ViewChild(MatSort) sort: MatSort;
+  @ViewChild(MatSort, { static: true }) sort: MatSort;
 
   constructor(
     private bs: BackendService,
diff --git a/src/app/workspace/results/results.component.ts b/src/app/workspace/results/results.component.ts
index f68d360c349693e18085c0d2ebe1df767ce4390f..bf31c7361a653d6a01c935857767b056856cf929 100644
--- a/src/app/workspace/results/results.component.ts
+++ b/src/app/workspace/results/results.component.ts
@@ -25,7 +25,7 @@ export class ResultsComponent implements OnInit, OnDestroy {
   public dataLoading = false;
   private workspaceIdSubscription: Subscription = null;
 
-  @ViewChild(MatSort) sort: MatSort;
+  @ViewChild(MatSort, { static: true }) sort: MatSort;
 
   constructor(
     private bs: BackendService,
diff --git a/src/app/workspace/syscheck/syscheck.component.ts b/src/app/workspace/syscheck/syscheck.component.ts
index c1706cda0f7d7554aad236a0a8386c357d15078f..b95e5d3032f3740e54b5f0d6c26e69dbec6c8170 100644
--- a/src/app/workspace/syscheck/syscheck.component.ts
+++ b/src/app/workspace/syscheck/syscheck.component.ts
@@ -22,7 +22,7 @@ export class SyscheckComponent implements OnInit {
   public tableselectionCheckbox = new SelectionModel<SysCheckStatistics>(true, []);
   public dataLoading = false;
 
-  @ViewChild(MatSort) sort: MatSort;
+  @ViewChild(MatSort, { static: true }) sort: MatSort;
 
   constructor(
     private bs: BackendService,
diff --git a/src/environments/environment.ts b/src/environments/environment.ts
index 82b5a8a4500c447161229a4b94220e3fd9ca0cf2..ba15a39872219e2c326bdcff5f0f1a5533601694 100644
--- a/src/environments/environment.ts
+++ b/src/environments/environment.ts
@@ -5,7 +5,7 @@
 
 export const environment = {
   production: false,
-  testcenterUrl: 'https://itemdb2.iqb.hu-berlin.de/admin/',
+  testcenterUrl: 'http://localhost/2020/testcenter-iqb-php/admin/',
   appName: 'IQB-Testcenter Verwaltung',
   appPublisher: 'IQB - Institut zur Qualitätsentwicklung im Bildungswesen',
   appVersion: '0.5 (dev)'
diff --git a/tsconfig.json b/tsconfig.json
index 9187c607b2931b806cbba7e9709c2546fb2c7be1..d47546887c691397afbe24aea3e0d2fbd5ccefc1 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -18,6 +18,14 @@
     "lib": [
       "es2017",
       "dom"
-    ]
+    ],
+    "paths": {
+      "core-js/es7/reflect": [
+        "node_modules/core-js/proposals/reflect-metadata"
+      ],
+      "core-js/es6/reflect": [
+        "node_modules/core-js/proposals/reflect-metadata"
+      ]
+    }
   }
 }