Thread:Extension talk:Flow/ flow-action-unsupported/reply

What happens when you visit a new page in the main namespace? If you've commented out $wgFlowOccupyNamespaces then you should be able to edit the empty page as simple wikitext. As I recall, Flow behavior around January was as follows: if Flow occupies a namespace then when someone first visits a page in it Flow creates a dummy edit that changes the content type to 'flow-board'. Changing $wgFlowOccupyNamespaces doesn't undo this, you have to change the content type back to wikitext. You might be able to do this by View History of an occupied page, find this change and undo it, but there have been bugs with this.

Disclaimer: I used to work on Flow, my understanding is out of date.