I can't find any changes regarding to 2.1.0 update, so I need an explanation.

My addon ( http://files.wowace.com/PallyPower/PallyPower.zip ) uses secured templates and worked fine pre 2.1.0, but it has failed to work even out of combat on PTR.

The offending functionality seems to be related to spell casting using buttons derived from Secure Action Button templates.

The following button assigns atrributes to cast buttons:

function PallyPower:UpdateLayout()
...
     -- left click (target a specific player and do 15 minute buff)
     pButton:SetAttribute("type1", "spell");
     pButton:SetAttribute("unit1", unitid);
     pButton:SetAttribute("spell1", gspell);
     -- right click (target a specific player and do 5 minute buff)
     pButton:SetAttribute("type2", "spell");
     pButton:SetAttribute("unit2", unitid);
     pButton:SetAttribute("spell2", spell);
...
end

Clicking on such buttons even out of combat causes an error message: PallyPower has been blocked from an action available to the Blizzard UI. What's going on?

This is a bug which is fixed for the next test realm update. :)