Seeing that nobody else has responded, I'll offer what little I know to bump your post so (hopefully) it gets noticed by a member with more specific information.

The error message usually means that some water has worked it's way down into the base which is a kind of containment tub. That triggered a float valve which shuts down the wash and the machine then tries to drain itself. Miele's dishwashers have a similar system, as do Bosch's current models of DWs and washing machines. The first thing I would check would be to open the access door at the lower left and check the cap on the drain/coin-trap. Is the cap tight? Can you see water in the base? If you loosen the cap, be prepared with a pan and towels as water can splash out, sometimes a lot. This process is described in the Miele owner's guides that I've seen, so maybe it is in your washer's guide.

After that, I would suspect an oversudsing event. Too many suds can impede drainage and cause the tub to overflow a bit. Sometimes water can seep out past the door gasket. That would be consistent with the water on the floor in front of the machine as well as water in the base's containment tub. I think the owner's guide may explain what to do about this.

Another possibility would be a problem with the door gasket. Perhaps a small hole has been worn in the gasket or maybe that the catch has worn on the door's gasket ring clamp so that it has stopped clamping. If this were one of last decade's Frigidaire front loaders (like mine), I would check to see if the door was fully latched. Dunno if it would be the same for your model Miele washer, but on my old Frigidaire, the latch striker can wear and may enough flex for some water to pool in front of the machine.

One other suggestion would be to try search at automaticwasher site; here's a link.

The repair guy is scheduled to come in Monday morning, so I think I'll leave the machine as is for now so he can see what happened. Interesting that over sudsing can cause this and that is what I might have suspected since I have been somewhat lax with measuring detergent, especially since I started using a laundry rinse product. However, the suds were a lot less than I have had at instances in the past (I used less detergent this time), and it appears this problem happened during one of the rinses because the clothes were just wet with no detergent on them when I pulled them out of the machine. Let us see what the repair guy says on Monday. I will report back.

Incidentally, I have an installer coming in today to install a Miele 4228 dishwasher. So a few days of appliance stuff for me.

So tech came in a first ran a rinse & spin cycle. It immediately started leaking. Turns out a hole in the boot (is that what it's called?) was the problem. He didn't have the part and said it would probably take a couple of days to get one.

Boot was replaced and machine is up and running just fine. I asked what causes this. He said said something is causing the rubber to almost disintegrate. He demonstrated by stretching it and poking several holes in it with his finger. This is specifically near the existing hole. As he got away from it, i.e. towards the top of the boot, he couldn't stretch and pierce holes with his finger.

Also noticed a ton of crud at the top section. Does everyone have this? I normally just wipe the bottom after each use. In the picture below, the boot has been removed and is on a table and I'm stretching open the top groove to expose the build up of "gunk", so ignore the orientation.

I'll try to pay attention and see if it happens with the new one too, although it's really hard to view that area when it's in the machine especially with my bad back.

Incidentally, the boot is made in Poland, not Germany.

How old is the machine? you mention a “laundry rinse product” you use? I’m surprised the service tech didn’t have any ideas. Glad it’s fixed, but you’re right to find out what caused it. I have had my W1 just a year and a few months. No gunk and no visible wear to the boot.

The machine is a little over 4 years old. I run it almost every other day. I only started using the rinse product about a year ago, so the build up may have been from before that time.

what is the rinse product?

Sonett Laundry Rinse.

https://www.sonett.eu/products/waschen/laundry-rinse/?L=1

(Their website is awfully slow today.)

Doe this mean in the worst case I could be getting 100% swirled water. :)

looks like a high percentage of citric acid and alcohol in there. I am no chemist but it seems that you are running a mini clean machine cycle every time you use that. Residual amounts are probably sitting in the boot and eating away at the boot material since it is soft at the bottom

if you are concerned about residual detergent I would run and water extra rinse and just make sure that you are using the proper amount of detergent first.

Interesting. I specifically showed the rinse to the repair person and he looked at the ingredients and said they are fine and they would not be the cause of eating away at the boot. He was very negative about detergents with enzymes.

I also wipe the boot dry after each use.

I have been using the rinse only for a year or so.

I have since started using less detergent so at least for now there is no excessive sudsing.

if it was a hole then I would assume some sharp object that got caught in the laundry and then snagged the boot. If the material is soft (especially only at the bottom) , then I would look at chemistry.

I have had a Miele since 2005 and no issues in the boot area (or anywhere else for that matter). My model was the last of the 220v builds

Unless there is an overriding issue, I would stop using the rinse. Usually simpler is better.

Actually repair guy was a able to puncture it with his finger in the areas around where the original hole was. He tried to do the same thing (puncture with finger) away from the hole but it didn't happen (this would be the side/top of the boot). If it was caused by a sharp object I would think he would not be able to puncture it with his finger.

I don't know if it's fair to make comparison to a machine from 2005 because we are now in a modern economy where companies have figured out how to engineer the quality out of a product while it still looks identical to the old one.

I started using the rinse because it was recommended by my towel manufacturer when I complained the towels were getting stiff. They went through how I was washing it (temp, cycle type, brand of detergent, etc.) and recommended the rinse. Using the rinse fixed the problem and in fact made all of my clothes feel a lot softer. I would not want to stop using the rinse unless I was also switching detergents to something known to rinse out more easily.

The rinse product anoop is using functions as a laundry sour ... it's slightly acidic to counteract the alkalinity of detergent.

I know this an older thread, but this is a new problem for my MIL. Her Miele had some water underneath it yesterday and the "Waterproof system activated" message. She did unplug the washer, but when she plugged it back in, the message was still there. It is possible it was an oversudsing event based on the usage in that household. The washer is a 2013. I was hoping I could get some ideas about how to clear the default so we don't incur a repair fee. I read the above messages, but was wondering if there is anything a layman can do until I can get there and check the draintrap and the boot. I don't think she uses caustic additives or FS. We have already replaced the refrigerator and oven in the last few months, and I am trying to avoid a new washer expense if possible.

I doubt over sudsing would result in a leak. Is it not possible for her to check the boot? I had a second instance of this happen a couple of years ago and as a temporary fix I used Gorilla tape to cover the hole and keep using the machine until the boot could be replaced.

Thanks anoop. I will have her check that herself until I can get over there myself. Based on your responses above I was planning on looking at that first thing.

Well so much for Miele reliability and longevity. Miele repairman says it is the motherboard at a cost of $900. Machine not quite 12 years old. Needless to say, we are NOT replacing it with another Miele.

Thanks for the follow up. 12 years is pretty good. If the rest of the machine is in good shape, it may be worth fixing. Most machines are decent but check the reviews you’ll see they fail ealier — 5-7 years would be good. However Miele is a cut above in terms of fit and finish (no rough edges), drum design, efficiency, and cleaning effectiveness. I don’t know about their latest ones, but W3038 was designed to last 20 years.

I use about 1 tablespoon of liquid detergent for small loads and about double that for full loads.

Unless there is an actual leak (rare) , the number one reason for the waterproofing error code is over sudsing . Over sudsing is almost always caused by too much detergent .

I wouldnt be using pods for that washer - too much detergent added too early in the cycle. Expensive too .