Microsoft has rolled out an important emergency update for Windows 11 users following several issues that came up after the regular January 2026 security patch. This out-of-band update, known as KB5078127, came out on January 24, 2026, and targets problems that affected many people using the OS.
The January Patch Tuesday update caused trouble for some users right away. Reports came in about apps like Outlook Classic becoming unresponsive or crashing, especially when handling POP accounts or PST files. Some users also faced issues with cloud storage services such as Dropbox, where saving files led to hangs or failures. In certain cases, the problems made everyday tasks difficult, forcing people to look for workarounds like rolling back updates.
Microsoft quickly responded with this emergency fix to avoid further disruption. The company described KB5078127 as a cumulative update that includes all previous fixes along with the new corrections. It applies to Windows 11 versions 24H2 and 25H2. A separate but related out-of-band update, KB5078132, was released for version 23H2 to cover similar ground.
Users who installed the January security update and then noticed Outlook not working properly or apps freezing during file saves should install this update without delay. Microsoft has made it available through Windows Update, so most systems will pick it up automatically if automatic updates are turned on. For those who want to check manually, go to Settings > Windows Update > Check for updates.
This is the second emergency step Microsoft took in a short time. Earlier in January 2026, there were also reports of boot failures and sign-in errors linked to the main update, leading to initial out-of-band patches. The latest one focuses mainly on application stability and compatibility after those earlier adjustments.
Many users on forums and support pages have shared that installing KB5078127 resolved their Outlook crashes and made file-saving operations smooth again. Microsoft has confirmed the issues were tied to changes in how the update handled certain credential prompts and app interactions.
If you are on Windows 11 and have not yet seen this update, it is worth checking now, especially if you rely on Outlook or similar productivity tools. Keeping the system updated helps maintain security while fixing these practical bugs.
In short, this emergency Windows 11 update shows Microsoft’s quick action on user-reported problems. Install KB5078127 as soon as possible to get back to normal use and stay protected with the latest security improvements. Always back up important data before major updates, just to be safe.