Ionic back button is not displaying

I have Ionicv4 app, I am not understanding why my back button is not at all displaying. Could you please help me out.

.toolbar-background-md {
    border-color: #427feb;
    background: #427feb;
 <div class="toolbar-background-md">
 <ion-navbar primary >
          <img src="assets/icon/tetra_single.png"   style="width: 30px;height: 15px;margin-left: 5px;"  />

    <ion-nav [root]="rootPage" #content  swipeBackEnabled="true">

Do I need to add anything for my app

try this

       <ion-buttons slot="start">
        <ion-title> editProfile </ion-title>

But it is giving below error

Error: Template parse errors:
‘ion-back-button’ is not a known element:

  1. If ‘ion-back-button’ is an Angular component, then verify that it is part of this module.
  2. If ‘ion-back-button’ is a Web Component then add ‘CUSTOM_ELEMENTS_SCHEMA’ to the ‘@NgModule.schemas’ of this component to suppress this message. ("

    [ERROR ->]

    editProfile </io"): ng:///AppModule/TetraApp.html@10:13

are you using ionic 4 or ionic 3 ?

am using ionic 4. Now Issue was solved

How did you solve it?

For future reference for other people.

JUst add swipeBackEnabled=“true” to our app , It was already there in my above code… If you do swipe left to right it navigates to our previous page.