diff --git a/src/app/+search-page/search-filters/search-filter/search-facet-filter/search-facet-filter.component.ts b/src/app/+search-page/search-filters/search-filter/search-facet-filter/search-facet-filter.component.ts
index faaf3b9fb52d2bb0ab215e939ad0a772b57b833e..fd5a75e7d19e0ddb92d79adfdd04c4e7cd91e712 100644
--- a/src/app/+search-page/search-filters/search-filter/search-facet-filter/search-facet-filter.component.ts
+++ b/src/app/+search-page/search-filters/search-filter/search-facet-filter/search-facet-filter.component.ts
@@ -6,7 +6,7 @@ import {
   Subject,
   Subscription
 } from 'rxjs';
-import { switchMap, distinctUntilChanged, first, map, take } from 'rxjs/operators';
+import { switchMap, distinctUntilChanged, map, take } from 'rxjs/operators';
 import { animate, state, style, transition, trigger } from '@angular/animations';
 import { Component, Inject, OnDestroy, OnInit } from '@angular/core';
 import { Router } from '@angular/router';
diff --git a/src/app/+search-page/search-filters/search-filter/search-filter.component.ts b/src/app/+search-page/search-filters/search-filter/search-filter.component.ts
index ec239e362807ab9abf5e97453fb63437c857c65d..289b5da143995f6af10fec1fa79588ff50ade4ee 100644
--- a/src/app/+search-page/search-filters/search-filter/search-filter.component.ts
+++ b/src/app/+search-page/search-filters/search-filter/search-filter.component.ts
@@ -1,5 +1,4 @@
-
-import { first, take } from 'rxjs/operators';
+import { take } from 'rxjs/operators';
 import { Component, Input, OnInit } from '@angular/core';
 import { SearchFilterConfig } from '../../search-service/search-filter-config.model';
 import { SearchFilterService } from './search-filter.service';
diff --git a/src/app/app.component.ts b/src/app/app.component.ts
index 98e0d614ae44b6dc36ad77bdd8a422eecd1fbefd..30a8f012511559cf6024567d3b4455dadddeaa2e 100644
--- a/src/app/app.component.ts
+++ b/src/app/app.component.ts
@@ -1,4 +1,4 @@
-import { filter, first, map, take } from 'rxjs/operators';
+import { filter, map, take } from 'rxjs/operators';
 import {
   AfterViewInit,
   ChangeDetectionStrategy,
diff --git a/src/app/core/auth/auth.effects.ts b/src/app/core/auth/auth.effects.ts
index 56a5411ef2175d50268fc6c568afcd725fa91924..1e68802af88928796835bc19b1d78ec5b9cef390 100644
--- a/src/app/core/auth/auth.effects.ts
+++ b/src/app/core/auth/auth.effects.ts
@@ -1,6 +1,6 @@
 import { of as observableOf, Observable } from 'rxjs';
 
-import { filter, debounceTime, switchMap, take, tap, catchError, map, first } from 'rxjs/operators';
+import { filter, debounceTime, switchMap, take, tap, catchError, map } from 'rxjs/operators';
 import { Injectable } from '@angular/core';
 
 // import @ngrx
diff --git a/src/app/core/auth/auth.service.ts b/src/app/core/auth/auth.service.ts
index 66fe65a22ede3fc16dc6a75912abdc6cfa34aa7e..6a2b4afa6ec73ef53d78e377103d8f30a00b0c72 100644
--- a/src/app/core/auth/auth.service.ts
+++ b/src/app/core/auth/auth.service.ts
@@ -2,7 +2,6 @@ import { Observable, of as observableOf } from 'rxjs';
 import {
   distinctUntilChanged,
   filter,
-  first,
   map,
   startWith,
   switchMap,
diff --git a/src/app/core/auth/server-auth.service.ts b/src/app/core/auth/server-auth.service.ts
index 903926fbcfb9dc25f36e3dac40cfa70a3f0c0de6..25ec1156eef16f8418ff4ac107a09e014ab73677 100644
--- a/src/app/core/auth/server-auth.service.ts
+++ b/src/app/core/auth/server-auth.service.ts
@@ -1,4 +1,4 @@
-import { first, map, switchMap, take } from 'rxjs/operators';
+import { map, switchMap, take } from 'rxjs/operators';
 import { Injectable } from '@angular/core';
 
 import { Observable } from 'rxjs';
diff --git a/src/app/core/cache/builders/remote-data-build.service.ts b/src/app/core/cache/builders/remote-data-build.service.ts
index 62a49927872798b7f8d1680739f38e9a53b81ff9..7561fe3affc74ea46f51714bc252c9095a89b21d 100644
--- a/src/app/core/cache/builders/remote-data-build.service.ts
+++ b/src/app/core/cache/builders/remote-data-build.service.ts
@@ -7,7 +7,6 @@ import {
 import { Injectable } from '@angular/core';
 import {
   distinctUntilChanged,
-  first,
   flatMap,
   map,
   startWith,
diff --git a/src/app/core/cache/object-cache.service.ts b/src/app/core/cache/object-cache.service.ts
index 40f41be14d9ccd74eaa5dbca1ddfe7fe418f98c4..af30646f53c963df45fc6005262e70b03d1d25cc 100644
--- a/src/app/core/cache/object-cache.service.ts
+++ b/src/app/core/cache/object-cache.service.ts
@@ -1,6 +1,6 @@
 import { combineLatest as observableCombineLatest, Observable } from 'rxjs';
 
-import { distinctUntilChanged, filter, first, map, mergeMap, take, } from 'rxjs/operators';
+import { distinctUntilChanged, filter, map, mergeMap, take, } from 'rxjs/operators';
 import { Injectable } from '@angular/core';
 import { MemoizedSelector, select, Store } from '@ngrx/store';
 import { IndexName } from '../index/index.reducer';
diff --git a/src/app/core/cache/server-sync-buffer.effects.ts b/src/app/core/cache/server-sync-buffer.effects.ts
index d0a194705b1ee728f35e324250506bab7699e956..0d7392e555bf302747f2d0402955bae846fcb643 100644
--- a/src/app/core/cache/server-sync-buffer.effects.ts
+++ b/src/app/core/cache/server-sync-buffer.effects.ts
@@ -1,4 +1,4 @@
-import { delay, exhaustMap, first, map, switchMap, take, tap } from 'rxjs/operators';
+import { delay, exhaustMap, map, switchMap, take } from 'rxjs/operators';
 import { Inject, Injectable } from '@angular/core';
 import { Actions, Effect, ofType } from '@ngrx/effects';
 import {
diff --git a/src/app/core/data/data.service.ts b/src/app/core/data/data.service.ts
index 6afc84df5a957a86ea7687b816fb7dc926f412b9..0921592a836c75ad8deff405d6645fe819e90a22 100644
--- a/src/app/core/data/data.service.ts
+++ b/src/app/core/data/data.service.ts
@@ -1,4 +1,4 @@
-import { delay, distinctUntilChanged, filter, find, first, map, take, tap } from 'rxjs/operators';
+import { filter, find, map, take } from 'rxjs/operators';
 import { Observable } from 'rxjs';
 import { Store } from '@ngrx/store';
 import { hasValue, isNotEmpty } from '../../shared/empty.util';
@@ -14,7 +14,6 @@ import { NormalizedObject } from '../cache/models/normalized-object.model';
 import { compare, Operation } from 'fast-json-patch';
 import { ObjectCacheService } from '../cache/object-cache.service';
 import { DSpaceObject } from '../shared/dspace-object.model';
-import { of } from 'rxjs/internal/observable/of';
 
 export abstract class DataService<TNormalized extends NormalizedObject, TDomain> {
   protected abstract requestService: RequestService;
diff --git a/src/app/core/metadata/metadata.service.ts b/src/app/core/metadata/metadata.service.ts
index 9a74de992e83484dc664657c508b2d1403086076..136bfe8f3e19c368d681254283b60e302037955a 100644
--- a/src/app/core/metadata/metadata.service.ts
+++ b/src/app/core/metadata/metadata.service.ts
@@ -2,7 +2,6 @@ import {
   catchError,
   distinctUntilKeyChanged,
   filter,
-  find,
   first,
   map,
   take
diff --git a/src/app/core/shared/operators.ts b/src/app/core/shared/operators.ts
index d9b41ebd734213bb84e97412686a46a87a428deb..550ef0916379f9e470dcbe533c27a07bf9bf7597 100644
--- a/src/app/core/shared/operators.ts
+++ b/src/app/core/shared/operators.ts
@@ -1,5 +1,5 @@
 import { Observable } from 'rxjs';
-import { filter, find, first, flatMap, map, tap } from 'rxjs/operators';
+import { filter, find, flatMap, map, tap } from 'rxjs/operators';
 import { hasValue, hasValueOperator, isNotEmpty } from '../../shared/empty.util';
 import { DSOSuccessResponse, RestResponse } from '../cache/response.models';
 import { RemoteData } from '../data/remote-data';