That's the problem with software; there is one happy path and an infinite number of unhappy ones. I've had applications run for years and then get an issue because some user did some series of steps that the application has never seen before or want to do something reasonable that nobody thought of before.

It's the nature of the beast.

To some extent, of course.

Here it seems that the built-in feature to change the primary e-mail address of one of the biggest VoIP services in the world was never actually tested properly and breaks your account by default. It’s bizarre how broken Microsoft’s account system is.

I’m actually surprised I haven’t yet heard of people having their GH/MS accounts break in unexpected ways due to linking them.

The problem is this case it was never designed to work this way from the start. It's a bunch of cobbled together systems, some from acquisitions, that are now forced to play nicely together.

As much as we like to think that Microsoft has infinite resources to re-write everything, they really don't. They have the same problems the rest of us have. Now I have to get back to figuring out why a half dozen users from our HR system are failing to import.

EDIT: Those users failed to import because the vendor changed an internal column name last week that is exposed in the export (and now it even has a typo). Ah, The joys of software development.

At least in your case, someone is fixing it. In MS case, the broken windows seem to stay that way and pile up eternally and I'm not even sure if the engineers who could fix them become aware of them. I did get escalated/sent around to a bunch of different people, seemingly all at different levels of indirection. I assume the issues are still exactly the same several years later.

For me, the bigger issue is that the problem was not resolved.

I had a very similar issue with Minecraft and Family accounts where the credit went to the wrong account. Microsoft just wouldn’t support this issue so I ended paying for something twice.

This is the nature of MS

I come from a testing QA background, and I will steal this quote, it is marvelous: "That's the problem with software; there is one happy path and an infinite number of unhappy ones."

A bit of a wow for me was when I learned about exit statuses: 0 is success, everything else is error because there is only one way that a command can do what you want and hundreds of ways it can fail.

It might seems obvious, but that seriously taught me something.

I had a similar issue with my Android phone at a certain point deciding that my work login (which is a GSuite account) was my main one, and breaking everything for several days. I can't remember how I got it fixed, but it's another example of how things can get very tricky when the "user" is the same as the "online account."