If your forum has Facebook-Connect enabled, then W3C validator won't let it pass unless you place Facebook meta code inside HTML-Comment as follows:
The reason is that Facebook reads the code inside comments while W3C ignores it.
Result is a valid page with functional FB-Connect.
(Thread here)
- ACP > Styles & Templates > Style Manager > Expand Templates > Facebook Templates > facebook_opengraph
- Add before the first line: HTML Code:
<--
- Add after the last line: HTML Code:
// -->
The reason is that Facebook reads the code inside comments while W3C ignores it.
Result is a valid page with functional FB-Connect.
(Thread here)