Clear all caches blank screen with new 8.5.1

Got a new clean setup install of 8.5.1

When I click on the ” Clear all caches ” button, I get a blank screen and have to go back.

To clarify the rest of the site works fine and going back works fine.

Just a glitch I would like to resolve.

The Browser Console shows:

location.ancestorOrigins is undefined  showNeg.js:115
style.sheet.addRule is not a function  include.preload.js:494
Loading failed for the <script> with source “”.  x_x-frustrated-with-this-blank-screen-submit-problem:508
Loading failed for the <script> with source “”.  x_x-frustrated-with-this-blank-screen-submit-problem:1
location.ancestorOrigins is undefined  showNeg.js:115

Th Administration theme is Seven.

Not sure what to check ?????????????

Drupal version: