1. McD HQ mandates franchises buy a special model Taylor-Made machine (not the same that like Chick-fil-a and others use). This is why McD machines stop working but other companies don't.
2. Every night there is a very specific maintenance routine that needs to be ran to clean and prep the machine for the next day. If it's not followed perfectly, the process will likely fail and the next morning workers will be greeted to a cryptic error code. Sometimes re-running the process will clear it, sometimes it wont. But this can take hours.
3. If re-running it doesn't fix it, then the franchise owner is stuck with the dilemma of bleeding money not having a working ice cream machine for customers, or calling an expensive hourly certified Taylor-Made repair person.
4. So they usually end up calling the repair person.
The idea is that McD HQ is working with Taylor-Made to make this problem happen so that franchise owners have to pay for expensive repair people.
Apparently the error codes have been reverse-engineered with a USB device that a third party created. But Taylor-Made is said to deny warranty and service etc if you try to use one.