I am doing one project, and as far as I am doing it I'm checking it for W3C errors (using html validator plug-in for Firefox), and in this process I found a warning that never showed up to me ever before.
"Warning: This interface to HTML5 document checking is deprecated"
- So, first thing came up to my mind, "let me Google this" and see what information I could find about this warning. But I didn't get anything.
- I tried another approach, which was going to the actual W3C Validator and see the outcome. I was given the same warning (shown below), but this time it was pointing me to a different link to check again, which I did, but I couldn't understand why I had to check in W3C validator NU and not in W3C validator original as usual.
This interface to HTML5 document checking is deprecated. Use the Nu Html Checker at https://validator.w3.org/nu/ directly instead.
So what is the meaning of this warning and why it shows up?
P.S. - I just noticed this is happening across my current projects and AFAIR since a few days ago.