diff --git a/server/src/controllers/analytics_controller.ts b/server/src/controllers/analytics_controller.ts
index cbe5584..9edacdc 100644
--- a/server/src/controllers/analytics_controller.ts
+++ b/server/src/controllers/analytics_controller.ts
@@ -99,6 +99,9 @@ export function terminate() {
 
 async function runTask(task: AnalyticsTask): Promise<TaskResult> {
   return new Promise<TaskResult>((resolver: TaskResolver) => {
+    if(!analyticsService.ready) {
+      throw new Error(`Can't send task, analytics is not ready`);
+    }
     taskResolvers.set(task.id, resolver); // it will be resolved in onTaskResult()
     analyticsService.sendTask(task);      // we dont wait for result here
   });
@@ -291,15 +294,23 @@ export async function runDetect(id: AnalyticUnit.AnalyticUnitId) {
   }
 }
 
-export async function remove(id: AnalyticUnit.AnalyticUnitId) {
-  let task = new AnalyticsTask(id, AnalyticsTaskType.CANCEL);
-  await runTask(task);
+export async function remove(analyticUnitId: AnalyticUnit.AnalyticUnitId) {
+  await cancelAnalyticsTask(analyticUnitId);
 
   if(dataPuller !== undefined) {
-    dataPuller.deleteUnit(id);
+    dataPuller.deleteUnit(analyticUnitId);
   }
 
-  await AnalyticUnit.remove(id);
+  await AnalyticUnit.remove(analyticUnitId);
+}
+
+async function cancelAnalyticsTask(analyticUnitId: AnalyticUnit.AnalyticUnitId) {
+  try {
+    let task = new AnalyticsTask(analyticUnitId, AnalyticsTaskType.CANCEL);
+    await runTask(task);
+  } catch(e) {
+    console.log(`Can't cancel analytics task for "${analyticUnitId}": ${e.message}`);
+  }
 }
 
 export async function deleteNonDetectedSegments(id, payload) {
diff --git a/server/src/services/analytics_service.ts b/server/src/services/analytics_service.ts
index 8ce5b53..c352379 100644
--- a/server/src/services/analytics_service.ts
+++ b/server/src/services/analytics_service.ts
@@ -32,7 +32,7 @@ export class AnalyticsService {
 
   public async sendTask(task: AnalyticsTask): Promise<void> {
     if(!this._ready) {
-      return Promise.reject("Analytics is not ready");
+      throw new Error('Analytics is not ready');
     }
     let method = task.type === AnalyticsTaskType.PUSH ?
       AnalyticsMessageMethod.DATA : AnalyticsMessageMethod.TASK
diff --git a/server/src/services/data_puller.ts b/server/src/services/data_puller.ts
index 4ab4209..ee9b535 100644
--- a/server/src/services/data_puller.ts
+++ b/server/src/services/data_puller.ts
@@ -165,7 +165,10 @@ export class DataPuller {
       }
 
       try {
-        const time = this._unitTimes[analyticUnit.id]
+        const time = this._unitTimes[analyticUnit.id];
+        if(time === undefined) {
+          throw new Error(`Analytic unit ${analyticUnit.id} is deleted from puller`);
+        }
         const now = Date.now();
         const res = await this.pullData(analyticUnit, time, now);
         this._grafanaAvailableConsoleReporter(true);