Critical Warning: Synopsys Design Constraints File file not found

Actually, the MOST "most effective solution here" (probably) is to understand that quartus v12 (and possibly other versions, but not v9.0 to my knowledge) has problems accessing files over some networks, like those used by virtual machines for one example. The symptoms are random crashes and more often, claims that this file or that was not found (including default TimeQuest templates) or that you do not have permission to write to some folder that you actually do.

So if you were are working with networked files when the OP's error message appeared, try moving the project to a local disk instead and see what happens.

Oh and, AFAIK you do NOT have to create your own timing constraints file, just to get a good compile. A default set of rules will be used.

P.S: imho, a "rtfm" reply is worse than no reply at all. please resist the temptation to patronise people who are simply trying to get a little community help / interaction. such behaviour is hardly welcoming. ask yourself, if all answers could be found by simply "r'ingtfm" then wtf is this forum even here for?