Thumbnail doesn't show for website homepage when sharing on Facebook

Hello,
We had an issue last where image was not crawled from og:image tag by our Widget, but this is fixed now.
Can you please re-check this again and let us know the link to your website so that we can have a look at this if this is still happening.

Regards,
[moderated]

Hello,
I have the same problem.my website https://www.vasiliskouroupis.com doesn’t show any image when i share it on fb except the About page which show and an image and some words.. I am looking how to fix it many days but i can’t.i can t understand where can i write the codes. thanks!

We tried to check your website, but seems that the site is under maintenance or yet to launch.
We are getting the message – https://screencast.com/t/HqSFfYlkJ

Please note that Facebook crawls the page to decide how to display it. For that it uses Open Graph Tags present on the site.
In order to specify the share data of your choice, you will have to add open graph tags in the header of each page of your site.

For more info about og tags , you can visit the page:
https://support.sharethis.com/customer/portal/articles/475079-share-properties-and-sharing-custom-information#Open_Graph_Tags