My keurig 2.0 is overflowing.What is causing it and how do I get it to stop?

It may need de-scaling. When my Keurig did what yours is doing, I filled the reservoir 3/4 way with white vinegar, and ran the machine repeatedly until it all passed through. I then re-used that vinegar and did the whole pass through 3 more times. that cleared it up. Did that 9 months ago. Use: 6 cups/day.
One other source of this problem are the metal pieces that punctures the top and bottom of the K-cup. Coffee grinds can find their way in there, and can be cleaned out with a paper clip or mini-pipe cleaner. But clogging of the bottom puncturer usually results in overflow, unless the top is also blocked.
Good Luck

make sure you have the cup size set appropriately, you may have it on a larger cup than the one your filling

Hi,

Here is a tip that I wrote that will give you some things to try that will helpyou get your Keurig coffee brewer workingagain.

Keurig CoffeeBrewer not making a full cup of Coffee
heatman101

]\[';
';

Hi,

Here is a tip that I wrote that will give you some things to try that will helpyou get your Keurig coffee brewer workingagain.

Keurig CoffeeBrewer not making a full cup of Coffee
heatman101

Hi,

Here is a tip that I wrote that will give you some things to try that will helpyou get your Keurig coffee brewer workingagain.

Keurig CoffeeBrewer not making a full cup of Coffee
heatman101

,.;
';
][\

Hi,
Check the bottom needle...it is plugged...
Here is a tip that I wrote that will give you some things to try that will helpyou get your Keurig coffee brewer workingagain.

Keurig CoffeeBrewer not making a full cup of Coffee
heatman101

Hi,

Here is a tip that I wrote that will give you some things to try that will helpyou get your Keurig coffee brewer workingagain.

Keurig CoffeeBrewer not making a full cup of Coffee
heatman101

Hi,

Here is a tip that I wrote that will give you some things to try that will helpyou get your Keurig coffee brewer workingagain.

Keurig CoffeeBrewer not making a full cup of Coffee
heatman101

';';\][][\

You should make sure you are measuring in the same cups they are alot of coffee makers measure in 6oz cups (I don't know why) but they do so over 10 cups that would be 20 oz difference

Have you cleaned the exit needle? Seem to be clogged up, more info here: http://www.keurig.com/help/B60_Use&Care_guide_spreads.pdf