According to Microsoft, a mysterious update that was pushed out to Windows computers all over the world on Sept. 30 was merely a test patch that was accidentally released.

A spokesperson for the company said that Microsoft "incorrectly published a test update," and that it is now currently removing the said update.

The mysterious patch caused a stir online, as users flocked to forums, websites and other social media to talk about the update, with some concerned that the Windows Update system of Microsoft has been compromised and that the update was a large-scale attack on Windows machines.

The patch, which was rated as an important one and was named KB3877432, appeared not as a security fix but as a supplemental language update. It had a size of 4.3MB, but the text for fields such as its name and description was gibberish. In addition, the parts labeled "more information and "help and support" contained inaccessible links.

A thread on the support forums of Microsoft regarding the mysterious update has been viewed over 40,000 times at the time of writing. Threads on the issue has also appeared on forums such as Reddit, with users also voicing their confusion about the said update on Twitter.

The accidentally released patch was pushed out to consumer computers powered by Windows 7. Enterprise customers that are using Windows Server Update Services did not receive the test patch.

It was not immediately clear what the contents of the accidentally released test patch were, and if it was capable of actually modifying files on Windows machines.

"It's not the first time someone [or probably these days some computer] in charge of the approve button approved something it wasn't supposed to approve," wrote Susan Bradley, a volunteer moderator on the Microsoft support forums.

In most cases, if users tried to install the patch, the installation failed. However, one user said that the patch was successfully installed, and that it caused his laptop to crash frequently, compromising his system and machine.

However, a separate report described the patch as harmless, contradicting what the user posted.

Nevertheless, the mysterious patch turned out to be Microsoft's fault and not caused by an external, malicious force, which should be good news for users that were worried that the Windows Update service was compromised.