I'm experiencing "Server not found" errors on wp-admin for some actions. Here are some steps that result to this error:
1. Go to Pages, then delete a page
2. Go to Trash >Tick the deleted page > Click on “Empty Trash” button
3. Page reloads to show "Server not found":
It looks like it is because the domain root becomes missing after the action. The issue happens also when you try to upload an image from Edit Page screen, then clicked on "Media Library" tab. Same issue occurs when trying to click "Save" on any plugin settings page.
This has definitely something to do with how the server is set up on our end. But I can't figure out which variables or constants are being used to get the domain root URL. The rest of wp-admin screens seems to work though, WordPress / Blog URL settings are confirmed correct.
Any ideas / input will be greatly appreciated.