I use htmlmetatags plugin. And using that i can add og:image to individual pages. But is there a way so that there will be a default og:image for whole wiki and if there is a specific og:image value using htmlmetatags plugin then that would be used instead of default.
Found a solution 😁😁😁😁😁
lawpage Found a solution
It's always helpful when you find a solution to share it for others who might be have the same problem.
Added semantic plugin,turned on og:image in configuration settings, then in the file lib/plugin/semantic/helper.php replaced two "null"s with "default.jpg" . Then uploaded a default.jpg in the root (inside media manager) .
Now it works fine.