After updating the code to latest master version on December 13th blog posts (new and old) that contain a "/" character in the title display a 404 error with the following page.
Posts without that character on the title display just fine.
The final URL is something like this:
I'm not sure what the URL looked like before but it worked just fine for more than a year or so.
Updating to latest master code on Dec 15th didn't resolve the issue.
**This is a regression.
Let me know if I can provide any more details.