Drain pan of refrigerator is filling up and overflowing onto the floor. This never happened before.

It's not unusual for a refrigerator to drip a little water on the floor after you replace the water filter-air trapped in the water dispenser system can make the water dispenser drip enough to overflow the drip tray below the dispenser. You can fix it by streaming a gallon or two of water through the dispenser to eliminate the trapped air.
If water drips on the floor from the back of the refrigerator, a leaking water inlet valve or cracked water system tubing could be the cause. A clogged or cracked defrost drain tube could also cause the leak. Defrost condensate water collects in the drain pan at the bottom of the refrigerator so a cracked or overflowing drain pan can also cause water to drip on the floor behind the refrigerator. Check the drain pan for cracks and clean out any foreign objects that may be inside the drain pan.
Excessive frost caused by a leaking door seal can also cause the defrost drain pan to overflow. Check the door gaskets and replace them if damaged.

Is the pan "level" under fridge? If not, it will not hold the amount of drainage that is put out and spill onto the floor.

Hi,

What kind of unit do you have? Its possible depending on the manufacture that a water line is the cause as it drips water into the pan causes the overflowing of the drain pan. Look for cracks in all the water line under the unit and you may have to remove the back and the water valve to see it. Good luck

I’m happy to help further over the phone at https://www.6ya.com/expert/gere_bf68e6055dd61249

on most fridges, you should be able to empty drain pan. Remove grill on bottom at the floor, and see if pan will slide out. Good-Day!

If your water filter is " thru the kick plate , at the bottom , replace the filter . I have found several times now , where the filter rubber seals , have leaked into the drain pan , causing it to over flow . You do not have to replace the filter housing , just the filter .

Hi, Is it bypassing the drain or is the drain plugged? The most common is that the drain hole gets iced up and them overflows onto the floor.
Just wanting clarifcation.

hi August.
Cause: A blocked defrost drain is one of the most common causes of water leakage. This happens when food particles or other debris clogs up the drain hose, which can lead to ice buildup and, eventually, water leaking out of the freezer and refrigerator.
3 common refrigerator problems you can easily fix yourself

The freezer drain hose will drain the defrost water into a drip pan at the bottom of the freezer. When this pan becomes full, it will leak water onto the floor. This is a regular maintenance task whenever the freezer defrosts. Empty the drip pan during the defrost cycle.
How to Fix Water Leaking From the Bottom of Freezer

Why is my fridge leaking water on the floor? If the refrigerator is leaking water it's possible that the refrigerator has a clogged or freezing defrost drain. If the defrost drain freezes the defrost water will overflow the drain and drip down to the bottom of the compartment, If enough water accumulates in the bottom it can run out onto the floor.
SOLVED Water leak in refrigerator Refrigerator

On the freezer side at the bottom of the freezer coil there is a drain. There should be a thin aluminium filiament attached to the defrost element and feeding down into the drain tube. This filiament conducts heat from the element down the tube preventing ice forming in the tube and keeping it clear.

Maybe your machine has a leaky door, letting moist air inside. Make sure your compressor area is lint free. The heat from the compressor is supposed to evaporate that water. Make sure the pan is exactly in the right place, level, not cracked.

for reallybsq
problem could be door seals not sealing completely and hence excessive ice formed on evaporator and excess water when it melts. however, i have found this problem many times with large larder fridges and really found no cure.

for guest.
towards the bottom of the back wall, there is a gulley with a drain hole in the middle. this drain is blocked. clear it with something flexible and make sure water flows away freely