Microsoft this week began blocking Windows 7 and 8.1 PCs equipped with the very newest processors from receiving security updates, making good on a policy it announced but did not implement last year.
But the company also refused to provide security fixes to Windows 7 systems that were powered by AMD's "Carrizo" CPUs, an architecture that was supposed to continue receiving patches.
The decree that led to the update bans, whether allowable or not under Microsoft's new policy, was revealed in January 2016, when the company said making Windows 7 and Windows 8.1 run on the latest processors was "challenging."
Microsoft then ruled that Windows 10 would be the only supported edition on seventh-generation and later CPUs and simultaneously dictated a substantial shortening of support of both editions.
The biggest impact was on Windows 7, because it had become the standard in enterprises -- Microsoft's most valued customers -- with deployment shares far north of 50%.
According to Microsoft, Windows 7 was to be fully supported on sixth-generation processors -- Intel's were dubbed "Skylake," AMD's included Carrizo -- until July 17, 2017. At that point, some Skylake-equipped PCs would continue to receive some security updates; other such PCs would get nothing.
Microsoft later walked back the cut-off, first by extending the end-of-support date to July 2018, then by repudiating the sixth-generation proclamation for those systems on a we'll-support-them list. The last move -- which took place in August -- meant that in most instances only seventh-generation and later processors from AMD and Intel were on Windows 7's and 8.1's no-go catalog.
Even so, Microsoft on Wednesday acknowledged that it had blocked updates from reaching machines equipped with AMD's Carrizo processor, then promised to correct the snafu.
"Microsoft intends to continue to support Windows 7 and Windows 8.1 with this processor and plans to address the issue causing the message in a future update," said Edison Pus, identified as a Microsoft representative, on the company's support forum. Pus did not specify when the update to the update would appear.
Because the update ban cannot be reversed by users, they must wait until Microsoft issues a correction. During the interim, their PCs will be vulnerable to exploitation of the vulnerabilities Microsoft patched on Tuesday.
Other users also encountered the update injunction, but in those cases the messages were deliberate. "Windows 7 keeps giving a warning that my Intel Core i7 (7700k) processor is not supported," reported someone tagged as DenverBraganaza, in a message posted Tuesday to Microsoft's support forum.
That CPU is one from Intel's seventh-generation architecture, codenamed "Kaby Lake," and thus is on Microsoft's no-no list for Windows 7 and 8.1.
Others, however, said that their PCs had been barred from this month's updates -- and future updates -- even though the processors are not seventh-generation, raising the issue of false positives from whatever test or diagnostic Microsoft used to determine whether to block the machine.
One false positive report came from a user whose machine ran an Intel processor introduced around the same time as Windows 7, and had been refused April's update for the OS.
That report, along with at least one other, were posted on AskWoody.com, a site operated by Woody Leonard, a Windows patch expert who writes for Infoworld. (Like Computerworld, Infoworld is an IDG publication.)
Microsoft did not immediately reply to a request for confirmation that it has officially begun enforcing the stop-support policy.