diff --git a/src/addons/messageoutput/airnotifier/pages/devices/devices.html b/src/addons/messageoutput/airnotifier/pages/devices/devices.html
index ea9e75d30..4c139ed64 100644
--- a/src/addons/messageoutput/airnotifier/pages/devices/devices.html
+++ b/src/addons/messageoutput/airnotifier/pages/devices/devices.html
@@ -34,7 +34,7 @@
                             </p>
                         </ion-label>
                         <core-button-with-spinner [loading]="device.updating" slot="end">
-                            <ion-toggle [(ngModel)]="device.enable" (ngModelChange)="enableDevice(device, device.enable)"
+                            <ion-toggle [(ngModel)]="device.enable" (ngModelChange)="enableDevice(device, !!device.enable)"
                                 [attr.aria-labelledby]="'device-'+ device.id " />
                         </core-button-with-spinner>
                     </ion-item>
diff --git a/src/addons/mod/assign/components/submission/addon-mod-assign-submission.html b/src/addons/mod/assign/components/submission/addon-mod-assign-submission.html
index c33f6ab4b..f2e9b2414 100644
--- a/src/addons/mod/assign/components/submission/addon-mod-assign-submission.html
+++ b/src/addons/mod/assign/components/submission/addon-mod-assign-submission.html
@@ -311,7 +311,7 @@
                         <!-- Outcomes. -->
                         <ion-item class="ion-text-wrap" *ngFor="let outcome of gradeInfo!.outcomes">
                             <ion-select *ngIf="canSaveGrades && outcome.itemNumber" [(ngModel)]="outcome.selectedId"
-                                interface="action-sheet" [disabled]="gradeInfo!.disabled" [cancelText]="'core.cancel' | translate"
+                                interface="action-sheet" [disabled]="!!gradeInfo!.disabled" [cancelText]="'core.cancel' | translate"
                                 [interfaceOptions]="{header: outcome.name }">
                                 <p class="item-heading" slot="label">{{ outcome.name }}</p>
                                 <ion-select-option *ngFor="let grade of outcome.options" [value]="grade.value">
diff --git a/src/addons/mod/data/fields/date/component/addon-mod-data-field-date.html b/src/addons/mod/data/fields/date/component/addon-mod-data-field-date.html
index 6ba094c34..211336f07 100644
--- a/src/addons/mod/data/fields/date/component/addon-mod-data-field-date.html
+++ b/src/addons/mod/data/fields/date/component/addon-mod-data-field-date.html
@@ -5,7 +5,7 @@
     <ion-modal [keepContentsMounted]="true">
         <ng-template>
             <ion-datetime id="datetime" [formControlName]="'f_'+field.id" [max]="maxDate" [min]="minDate"
-                [disabled]="searchMode && searchFields && !searchFields['f_'+field.id+'_z']" presentation="date"
+                [disabled]="!!searchMode && !!searchFields && !searchFields['f_'+field.id+'_z']" presentation="date"
                 [showDefaultButtons]="true" />
         </ng-template>
     </ion-modal>
diff --git a/src/addons/mod/survey/components/index/addon-mod-survey-index.html b/src/addons/mod/survey/components/index/addon-mod-survey-index.html
index 89f179c69..661324b93 100644
--- a/src/addons/mod/survey/components/index/addon-mod-survey-index.html
+++ b/src/addons/mod/survey/components/index/addon-mod-survey-index.html
@@ -55,7 +55,7 @@
 
                 <!-- Subquestion -->
                 <ng-container *ngIf="question.parent !== 0">
-                    <ion-radio-group [(ngModel)]="answers[question.name]" [required]="question.required" [name]="question.name">
+                    <ion-radio-group [(ngModel)]="answers[question.name]" [required]="!!question.required" [name]="question.name">
                         <ion-row class="ion-align-items-center ion-padding-horizontal" [class.even]="isEven">
 
                             <ion-col size="7">
@@ -71,7 +71,7 @@
                                 <ion-radio [value]="value + 1" [attr.aria-label]="question.num + '. '+question.text + ': ' + option" />
                             </ion-col>
                             <ion-col class="ion-hide-md-up" size="5">
-                                <ion-select class="ion-padding" [(ngModel)]="answers[question.name]" [required]="question.required"
+                                <ion-select class="ion-padding" [(ngModel)]="answers[question.name]" [required]="!!question.required"
                                     [attr.aria-labelledby]="'addon-mod_survey-'+question.name" interface="action-sheet"
                                     [name]="question.name" [cancelText]="'core.cancel' | translate"
                                     [interfaceOptions]="{header: question.text}">
@@ -94,7 +94,7 @@
                             </span>
                         </ion-col>
                         <ion-col size="5">
-                            <ion-select class="ion-padding" [(ngModel)]="answers[question.name]" [required]="question.required"
+                            <ion-select class="ion-padding" [(ngModel)]="answers[question.name]" [required]="!!question.required"
                                 [attr.aria-labelledby]="'addon-mod_survey-'+question.name" interface="action-sheet" [name]="question.name"
                                 [cancelText]="'core.cancel' | translate" [interfaceOptions]="{header: question.text}">
                                 <ion-select-option [value]="question.required ? '-1' : '0'" selected [disabled]="question.required">
@@ -109,7 +109,7 @@
 
                     <ion-item *ngIf="question.type === 0" class="ion-text-wrap" [class.even]="isEven">
                         <ion-textarea labelPlacement="floating" [(ngModel)]="answers[question.name]" [name]="question.name"
-                            [required]="question.required">
+                            [required]="!!question.required">
                             <p slot="label" [core-mark-required]="question.required">
                                 <strong>{{question.num}}.</strong> {{ question.text }}
                             </p>
diff --git a/src/core/components/iframe/core-iframe.html b/src/core/components/iframe/core-iframe.html
index 09a3734d9..87e1ad40a 100644
--- a/src/core/components/iframe/core-iframe.html
+++ b/src/core/components/iframe/core-iframe.html
@@ -1,5 +1,5 @@
 <!-- Display a loading until the iframe page is loaded. -->
-<core-loading [hideUntil]="!loading && (safeUrl || launchExternalLabel)" />
+<core-loading [hideUntil]="!loading && (!!safeUrl || !!launchExternalLabel)" />
 
 <!--The iframe needs to be outside of core-loading, otherwise the request is canceled while loading. -->
 <!-- Don't add the iframe until safeUrl is set, adding an iframe with null as src causes the iframe to load the whole app. -->
diff --git a/src/core/features/h5p/components/h5p-iframe/core-h5p-iframe.html b/src/core/features/h5p/components/h5p-iframe/core-h5p-iframe.html
index 7b7876d87..64e29d48f 100644
--- a/src/core/features/h5p/components/h5p-iframe/core-h5p-iframe.html
+++ b/src/core/features/h5p/components/h5p-iframe/core-h5p-iframe.html
@@ -1,4 +1,4 @@
-<core-loading [hideUntil]="iframeSrc" [fullscreen]="false">
+<core-loading [hideUntil]="!!iframeSrc" [fullscreen]="false">
     <core-iframe *ngIf="iframeSrc" [src]="iframeSrc" iframeHeight="auto" [allowFullscreen]="true" (loaded)="iframeLoaded()"
         [showFullscreenOnToolbar]="enableInAppFullscreen" [autoFullscreenOnRotate]="enableInAppFullscreen" />
     <script *ngIf="resizeScript && iframeSrc" type="text/javascript" [src]="resizeScript"></script>
diff --git a/src/core/features/viewer/pages/iframe/iframe.html b/src/core/features/viewer/pages/iframe/iframe.html
index f102eba35..c95932560 100644
--- a/src/core/features/viewer/pages/iframe/iframe.html
+++ b/src/core/features/viewer/pages/iframe/iframe.html
@@ -9,7 +9,7 @@
     </ion-toolbar>
 </ion-header>
 <ion-content>
-    <core-loading [hideUntil]="url">
+    <core-loading [hideUntil]="!!url">
         <core-iframe *ngIf="url" [src]="url" [allowAutoLogin]="autoLogin" />
     </core-loading>
 </ion-content>