Wrong Putting Green

Wrong Putting (Including Temporary Greens)

Question: - When I was playing to a temporary green my ball ended up on the proper green. Can I play my ball as it lies?

Answer: No.

As your ball lies on the wrong green (e.g. the main green when the flag is on a temporary green) you must not play the ball as it lies.
This rule only applies when your ball lies on the wrong green. If the position of the ball is such that you are standing on the wrong green and your ball is off the green then you do not get a drop and must play the ball as it lies.
You must drop the ball within one club length of the nearest point of relief. This point must not be in a hazard or on the putting green.  I
If you play the ball from the wrong green you incur a 2 shot penalty in Stroke Play or Loss of Hole Match play.

(R&A Rules 25-3b)

It is worth remembering that his rule applies if your ball lands on the practice putting green as this is also a "wrong green."