After Windows 8, Microsoft decided to make Windows 10 available to users. But why was Windows 9 never released? We will deal with this issue in the following.
After the release of Windows 8, naturally, all users were looking forward to the introduction of Windows 9, but in 2014, Microsoft surprised everyone with the introduction of Windows 10. But the reason for this decision largely goes back to Windows 8. This version of Windows, although it had innovative features, was not welcomed by users. The criticism was so great that Microsoft solved some of these problems with the release of Windows 8.1 in 2013, but still did not have much to say.
That’s why Microsoft executives used the number 10 to name the next version, to show users that Windows 10 is not just a regular update to the previous version of Windows, but offers much more attractive features overall. At the unveiling of Windows 10, a Microsoft executive said that due to the improvements made, it was not appropriate to use the name Windows 9 for this new version.

It also seemed that Microsoft initially intended to use the name Windows One for this version, but since Windows 1.0 was released in 1985, they were unable to do so. So they have probably decided to put a zero next to the number one and bring their new operating system as Windows 10 to users. In the world of marketing, there are no hard and fast rules for naming products, and in general, these explanations seem logical.
An unofficial reason: Windows 9 compatibility issues
However, the explanations provided by Microsoft did not convince all users, and so various theories were put forward in connection with this decision. One of these theories came up on the day Windows 10 was introduced by a Reddit user who claimed to be a Windows developer. He wrote that the main reason for Microsoft to drop the name of Windows 9 is that some older programs may confuse this version with Windows 95 or Windows 98.

Such a claim received a great deal of attention at the time, as newer versions of Windows were developed to run older programs. However, the programmers reviewed the Windows 95 and 98 code and concluded that the two versions of the program were known as version 4.00.95 and 4.10.1998, and therefore denied this claim.
However, not all programs are programmatically ideal, and some pay attention to the official name provided to check the Windows version. Therefore, Reddit’s user’s claim may be somewhat true.
Unlucky number 9 in Japan
On the other hand, a Microsoft employee may have told company executives that the number 9 in Japan is unlucky and that the market as a whole is very important to Microsoft. But in this case, no documents have been disclosed and it is just speculation. Whatever the reason, millions of Windows 9 users around the world are now using Windows 10.
Source: How To Geek