Why do I kep getting this lopping PHP warning message on my Windows Dev server

Warning: file_get_contents(C:/laragon/www/osclass/oc-content/plugins/): failed to open stream: No such file or directory in C:\laragon\www\osclass\oc-includes\osclass\classes\Plugins.php on line 452

That sounds like you are missing essential directories or file permission on them are incorrect

it's a standard install, I only just downloaded the zip file and extracted the contents onto my Laragon server, ran the installation - everything got the green tick to say permissions and everything was correct. Go to Market > Plugins and get warnings, very slow loading aswell.
The directory exist.

I may change server from Apache to Nginx to see if this makes a difference

@Lee
Thank you. I think problem is that in some cases there is search for product that already does not exists.
Problem will be fixed in 8.0.1

You can also fix it quickly in oc-includes/osclass/classes/Plugins.php

Find:
  public static function getInfo( $plugin )
  {

    if(!file_exists(osc_plugins_path() . $plugin)) {
Replace with:
  public static function getInfo( $plugin )
  {

    if($plugin == '' || !file_exists(osc_plugins_path() . $plugin)) {

Thanks MB Themes, that's it. working now, no php warnings.

Glad to hear that