Microsoft has concluded its investigation into a data deletion bug in the original shipping version of the Windows 10 October 2018 Update. And the software giant is now testing a fixed version of that Update with Windows Insiders.

“We will carefully study the results, feedback, and diagnostic data from our Insiders before taking additional steps towards re-releasing more broadly,” Microsoft’s John Cable explains.

And Microsoft certainly has a lot of explaining to do here, now doesn’t it?

Microsoft pulled the Windows 10 October 2018 Update last Friday, just three days after its initial release, because of customer reports of data loss. Given Microsoft’s terrible history with Windows 10 feature updates, this is alarming. And the evidence points conclusively to two problems I’ve raised again and again: Microsoft’s Windows Insider Program is inadequate for testing new Windows versions. And the software giant does not do a good job of triaging the data it collects. Put simply, Microsoft has a software quality problem.

Cable’s description of what happened reads like it was designed to minimize the company’s exposure to potential lawsuits. The problem wasn’t just isolated, he says: Reports of actual data loss were few, just “one one-hundredth of one percent of version 1809 installs.” But “any data loss is serious,” he finally admits.

Cable also claims that the damage was minimized because Microsoft “intentionally starts each feature update rollout slowly, closely monitoring feedback before offering the update more broadly.” But Microsoft actually rushed this release out the door, skipping the normal “Release Preview” phase of testing so that it could arbitrarily release the October 2018 Update last Tuesday, the same day as its media event. (And one week before Patch Tuesday.) It did this because it botched the previous feature update, the April 2018 Update, and almost missed shipping that in April entirely. This release was going to happen much more quickly.

One might argue that it’s good news that Microsoft discovered this problem early—only so-called “seekers” were impacted, after all—and that it’s good news this didn’t happen when the update was in broader release. Stop making lemonade: What this really shows is that Microsoft hasn’t learned its lesson from previous release debacles. And I’ll point out again that the embarrassing April 2018 Update delay at least happened before the public release. This one was actually later in the cycle. Again, it’s a software quality problem.

But what’s most astonishing about this affair is that Microsoft knew about these problems ahead of time.

“Prior to re-releasing the October 2018 Update our engineering investigation determined that a very small number of users lost files during the update,” Cable admits. He explains how the data loss happened. But not why Microsoft shipped the update in this condition regardless. It’s rather incredible.

Anyway, Microsoft has fixed it. Probably. And they’ll use their known-flawed testing techniques with telemetry from the inept Insider Program to validate that. And then ship it publicly, again.

Finally, if you were impacted by this flaw, Microsoft has established a support channel via phone and its retail stores to help customers set things right. But it sounds like more of a grief counseling channel.

“We cannot guarantee the outcome of any file recovery work,” Cable admits. “If you have manually checked for updates and believe you have an issue with missing files, please minimize your use of the affected device and contact us directly at +1-800-MICROSOFT.”

Good luck with that.