I dont know what to add further.!! Let me attempt one more time. 1) I just want to have custom template as popover 2) for that I imported MdbPopoverModule in app.module.ts 3) then on a img tag i wanted to display a custom popover so added relevant popover attributes as mentioned in previous code. 4) when we use [mdbPopover] initialized to template ref variable named as 'tenplate' it gives error. 5) if i write simply mdbPopover and initialize it to any string, it works and popover appears with no styles. 6) Thats all!! Just wanted to have custom template for popover on a image.Simple.

I am not sure if I understand your example correctly. Is this an example where the popover content runs over and over again? Hovering over an image inside a popover opens another popover with the same content?

I used this code:

<button
  type="button"
  class="btn btn-lg btn-danger"
  [mdbPopover]="tenplate"
  mdbPopoverHeader="Popover title"
>
  Click to toggle popover
</button>

<ng-template #tenplate>
  <div  style="border: 1px solid #000;" [innerHTML]="ste"></div>
  <img
    [src]="['assets/1.jpg']"
    class="card-img-top"
    placement="left"
    trigger="focus  hover"
    mdbPopoverTitle="Power vs Force"
    [mdbPopover]='tenplate'
    alt="..."
    [delayHide]="1500"
  />
</ng-template>

and I have no such error. Please add the complete code - along with the element that uses this template. Please add information as to what exactly this error refers to. Which part of the code triggers it.

    <ng-template #tenplate >
<div  style="border: 1px solid #000;" [innerHTML]="ste"></div>
<img
      [src]="['assets/1.jpg']"
      class="card-img-top"
      placement="left"
      trigger="focus  hover"
      mdbPopoverTitle="Power vs Force"
      [mdbPopover]='tenplate'
      alt="..."
      [delayHide]="1500"
    />

on the above code for [mdbPopover]='tenplate' it gives following error:

Type 'TemplateRef' is not assignable to type 'string'.ngtsc(2322)