Been 2 days I couldn’t check my files in and the SharePoint Designer keeps throwing below error on every Check In.
At last I found a fix on it.
The error was because I opened a Site using it’s IP Address, for example:
The solve is by opening that site using the Computer Name (in my case I’m working locally / LAN), for example:
If you’re working on the internet site, I think the fix is the same. Use FQDN, for example:
Hope this help.